History ThatOneBoss / MegaMan

* Halfway into King Stage 2, the game's first MarathonLevel, you'll face King Plane, a simultaneous PlatformBattle and AutoscrollingLevel over BottomlessPits. The Plane not only [[InterfaceScrew does not have a visible health bar]], but will also take any opportunity to send you plummeting to your death with its two main attacks: an unavoidable screen-clearing laser that takes many shots to cancel out and can wipe out nearly a third of your health on hit, and a RocketPunch that not only homes in on you, but will destroy any platform it hits, easily killing you if you're unlucky. While the boss is generous enough to [[BossArenaRecovery constantly provide power-ups in bubbles during the fight]], they are mixed in with [[BlindedByTheLight flashbangs that white out the screen for about a second]], more than enough time to slip into the abyss. Its weakness as Mega Man, Spread Drill, is difficult to hit it with due to how the boss bobs up and down, and its weakness as Bass, Treble Boost, drains energy very quickly during use and has to be bought from the shop for 200 bolts beforehand. If you die, [[ContinuingIsPainful it's back to the beginning of the mini-stage that comes before it as well]].

* The Yellow Devil from Wily Stage 1. Its difficulty stems from his attack pattern; he splits apart and flies across the room one piece at a time, and you have to have crazy good reflexes — or have to have memorized his pattern — to dodge him without getting hit. Once he's fully formed, his eye opens and fires a fast-moving projectile at you, then it closes and he starts flying across the room again. You only get a couple of seconds before the eye closes, and if you're trying to kill him with the Buster, the eye sometimes opens too high to hit. Not only that, but he takes forever and a day to die, even with powerful weapons like the Elec Beam, since you will probably get in only one shot. And when he changes sides after that, you have much less reaction time to dodge with because he's already on screen instead of off of it. And there are two LATER bosses before the final one, and with proper tactics, they aren't nearly as bad as this one.

* Doc Quick Man is just as fast and unpredictable as the original, but is also [[LightningBruiser larger and more resilient]]. He also deals far more CollisionDamage (8, as opposed to the original's 4), and due to the way that he runs and jumps all over the place, it's extremely difficult to avoid bumping into him. This is such a deadly threat that a common strategy is to get hit by his Quick Boomerangs ''on purpose''; they deal far less damage, and the resulting MercyInvincibility can be used to avoid a devastating collision. The two weapons he's weak against (Search Snake and Gemini Laser) are also hard to land a hit on him as well. If you happen to be doing a NoDamageRun, you might as well stop here, as you're very likely to get hit by something from him.
* Doc Wood Man has all the issues of the original Wood Man, but is even worse. Here, he has a Leaf Shield with a significantly larger hitbox than that of the original to match his larger build--large enough that you'll need to either do a pixel-perfect leap over it, or use Rush Coil (which consequently [[MortonsFork smacks you into the leaves coming from above]]). The Leaf Shield also deals a whopping 8 damage, as does direct contact with Doc Wood himself, meaning that he can very easily take you out in just 4 hits. Just like Quick Man, trying to do a NoDamageRun on him is potentially nerve-wracking, as the mentioned precise timing takes a lot of practice (unless if you know how to use Rush Jet correctly, which is already a GameBreaker).

* The final battle against the Wily Machine is an arduous task. It's one of three battles in the main Classic series that are ''three'' phases back-to-back with no breaks in-between[[note]]the first being the Wily Machine from ''6'' and the second being the Mega Mech Shark from this game; however, the former is widely regarded as an AnticlimaxBoss, and only the third and final phase of the latter is seen as overly difficult[[/note]], technically giving it the status of a MarathonBoss. It also comes directly after the traditional series BossRush, so if the player has exhausted all of their weapons' energy on the Robot Master rematches without an M-Tank to spare, things can get ugly. All three of his phases have their own problems as well: the first phase is a TennisBoss with large, bouncing eggs that take many hits to detonate and can only hurt him in his jaw, the second phase has powerful stomping and ramming attacks as well as a flame jet that can be extremely difficult to avoid, especially at close range, and the third and final phase, the Wily Capsule 9, is a heavy user of TeleportSpam and quick, deadly projectile patterns from anywhere on the screen with a weakness to Plug Ball, a weapon that is nigh useless against airborne targets.

* In a game with mostly easy bosses, [=MagicMan.EXE=] sticks out like a sore thumb. His main attack is a slow-moving flame that hits like a Mack truck, but what truly pushes him into this territory is that he's also a FlunkyBoss. He can summon up to two normal viruses at any time, and the types he summons are those that have difficult-to-dodge attack patterns (''especially'' when you've also got [=MagicMan=]'s attacks thrown into the mix), and because they'll be replaced as soon as they die, destroying them isn't even really an option. If you've been relying on your alphabet soup folder to get you this far in the game, prepare to keep on dying over and over again.

* [=ThunderMan.EXE=] remains in the back row and fields three thunder clouds that move back and forth on the rows. These can fire off paralyzing thunder balls, and attack [=MegaMan=] if their movement gets obstructed. This results in the player needing to do some fancy footwork to be able to land hits on [=ThunderMan=] while dodging the clouds. And due to plot circumstances, the first time you fight him, you have also lost all your chips with the exception of the ones in your folder, and you can't access the net to get new chips unless you beat him. In the Virtual Console rerelease, he has the potential to be ''even worse'' if the player has relied on the Gospel Breath chips (which can't hit anything in the back row) and hasn't upgraded the chip folder from time to time.

* You have to fight Bass twice in the storyline, though the first one is just a HopelessBossFight (you can't hurt him, and even if you use something that makes you invincible, his attacks ignore it). The second fight, however, is a pain to get through, because he still has his Life Aura, and he attacks ridiculously hard, so it may take you a few tries if you don't have the right chip folder, and he comes right before you fight [[FinalBoss Alpha]], which if you lose to, you'll have to fight Bass AGAIN.

* Duo gets less fondly remembered compared to the other final bosses of the series, despite being largely on par with the other series final bosses. This reputation arises from how ''[[EarlyBirdBoss early]]'' it happens compared to the other entries -- Counting postgame and all, Duo's first fight is in the first third of the game, compared to the other final bosses being fought around the two-thirds or three-quarters mark. This meant you had to make do with first-tier chips, and the Battlechip and Program Advance library in the fourth game was quite lackluster, just to make things more difficult. To rub it in, his back two columns are always empty, invalidating any chips that depend on striking a panel to do damage and further reducing the number of options the player has. Duo's fight feels fairer on subsequent playthroughs when the player has a more well-developed arsenal (like being able to access all six Souls), but the first round will be a pretty big hurdle to overcome.\\
If you've been reliant on the PurposelyOverpowered Dark Chips to get through the game, it pulls an unannounced VideoGameCrueltyPunishment by disabling your ability to use them. Now you're left with reduced maximum HP, no Soul access, and whatever folder you had on hand to begin with. No other final boss did this.

* Although the second encounter with Violen in the first stage of the X-Hunter Base can be tricky with his unpredictable mace ball, he pales in comparison to the boss of the following stage, the Serges Tank. The entire fight starts on [[PlatformBattle four vertically moving platforms]] over a floor of OneHitKill spikes, and you're only given around half of the screen to fight against it - the rest is taken up by the Tank itself. Its arsenal is fierce: the first phase consists of four durable vertically-placed cannons firing fast projectiles that either go straight forward or bounce along the floor. Once they're all destroyed, Serges reveals himself...but not before [[AdvancingBossOfDoom inching forward and destroying two of the four platforms]], leaving you with ''even less'' space and footing. Serges will then start moving up and down erratically while firing projectiles that alternate between exploding into Xs or +s. To make matters worse, not only is Serges [[AttackItsWeakPoint only vulnerable on his top half]], but he also tends to get very close to the spikes below, so even one mistake can result in a very difficult battle having to be restarted from scratch. The only saving grace is that you can skip the first phase destroying the four cannons with a [[SmartBomb fully charged Giga Crash]] at the beginning, leaving Serges exposed to your attacks, but even then, good luck landing hits on him.

* While Sigma himself is very pattern-based and easy to read, the true terror appears in the form of Kaiser Sigma, his gigantic battle body. Kaiser Sigma is so large that he fills up half of the arena you fight him in, and his weak spot is [[HitboxDissonance not his head, but rather the small "fins" directly above it]]. He has two patterns, one when you're behind him and one when you're in front of him. When you're behind him, he shoots [[MacrossMissileMassacre many homing missiles that hit extremely hard]], and when you're in front of him, he charges and fires a cone-shaped laser either upward or downward that [[CycleOfHurting continuously damages and stuns you when you get hit by it]]. All the while he's spawning tracking bombs. Only two things can damage him: charged X-Buster shots (in a game where the X-Buster upgrade actually [[PowerUpLetDown makes it more difficult to use]]), and the GameBreaker Z-Saber, which can take him down in only two hits, but get hit ''once'' while trying to slash him, and it'll be cancelled out. Even after you manage to kill him, it's not over, as you still have one last trial: wall-climbing a long vertical AutoscrollingLevel with the Sigma Virus trying to knock you into the damaging lava below. If he successfully manages to, it's entirely possible for you to get stuck in hitstun under one of several outcroppings in the shaft, and since the lava is treated as a solid floor, you can get crushed, in which case [[ContinuingIsPainful it's back to the beginning of Sigma's first form]].

** The first one is from a boat, and you're fighting several submarines and a few Draches, which can shoot torpedoes at your boat. After that, you fight the Balkon Gerät, a giant frog battleship-mecha, which will merrily chop your boat to pieces if you can't dish out damage fast enough. It's tame enough that you can get by with just your buster in Normal if you know what you're doing, but on Hard the entire thing basically mandates a maxed out Machine Buster and Hyper Cartridge to refresh your ammo for it.
** The battle against the Gesellschaft takes this up to eleven. You have to fight several Draches, the Gesellschaft itself, and then the HumongousMecha Focke-Wulf, one after another, with no continue points or opportunities to heal. You have to do it from the top of the Flutter, which is a small confined space and offers no defensive cover. The Flutter ''itself'' can take damage, there's no way of healing it, if it's shot down it's GameOver, and the ''enemies specifically target the Flutter over you''. You're also ''cut off'' from the town and any resources since the boss fight happens ''as you are leaving the dungeon and returning to town''. It is [[UnintentionallyUnwinnable technically possible]] to sabotage yourself so badly that you have no chance of winning, but fortunately even without being able to go back to town, they are very possible to take down by developing [[MoreDakka superior firepower]].

* The [[WolfpackBoss Karumuna Bash trio]], three doglike Reaverbots in the Sub-gate of the Clozer Wood. Those things are ''nasty'' if you're not CrazyPrepared for them. They all attack you at once and they are FAST. Their primary attack is jumping at you, which knocks Mega Man down and is possibly also a CameraScrew if you land right. Their other attack is to ''breathe fire'', which instantly depletes your life meter's shield so you can take MORE damage from their jump attack.

* And then there is Red. If you don't have Zero, good luck to you. You have to target Red from a distance. Since the camera enjoys screwing you, this becomes a problem. Dodging his attacks is problematic because you're not fighting on solid ground. You're fighting on platforms with a hole in between each one. Fall and you die. Get hit while jumping and you will die. He constantly teleports around on those platforms and there is no way to predict where he will end up. The only way to finish the fight quickly is to use Zero and take contact while slashing him.

* Spiral Pegasus/The Skiver, which is basically a tougher version of Storm Eagle; he boasts the same sort of attacks, but all vastly more difficult, coming from all directions at high speeds. To make up for the fact that he doesn't have similar pushing abilities as Storm Eagle, any contact with him will push X or Zero ''a lot farther''. If you collide into him next to one of the two [[BottomlessPit Bottomless Pits]] on the sides of the arena, you're probably going in. And making him a standout from every other boss in the entire series, he does not have an actual weakness to a specific power. Instead, he can be frozen with the Dark Hold, which doesn't last long enough to punch off a decent portion of his health.

* The fight with Gate is a TennisBoss and PlatformBattle hybrid over a BottomlessPit while he constantly gives chase and occasionally[[note]]often to the point of making the fight excessively long[[/note]] fires off random colored "gates" that have various detrimental effects[[note]]red ones slow you down, orange ones fire at you, green ones home in, blue ones have a vacuum effect, and purple ones generate [[DemonicSpiders Nightmare Viruses]][[/note]]. The only way to damage him is to attack the "gates" so they split into smaller projectiles that can hit him, but they can also damage ''you'', so you'll often find the both of you taking damage simultaneously. The red and blue "gates" are by far the most dangerous, as they greatly increase your chances of falling into the pit or getting knocked in. When he gets below half health, he gains an additional attack: ''breaking the platforms that you need to stand on to survive''. Not only can it easily kill you, but it also doesn't allow you to hit him in return. This fight is tedious, dangerous, and overall very frustrating.[[note]]Playing on Rookie Hunter mode in ''[[CompilationRerelease X Legacy Collection 2]]'' adds an indestructible floor over the pit, but it only makes the fight easier by so little.[[/note]]

* Apollo Flame. (He's also in the second game, but he's the final BonusBoss there as opposed to being fought halfway through the postgame.) He has a lot of HP, a barrier that regenerates, and a lot of attacks that either can't be blocked or keep you from hitting him until his barrier comes back. It's easier if you have Cancer or Virgo Noise, and infinitely harder if you have Ophiuca or Wolf Noise.

* Basically every boss in this game elevates to this level in [[BossRush Boss Survival mode]]. You're given only the default-length life and weapon gauges, two sub tanks, and a single life to try and kill 16 bosses in a row. Damage carries over between fights, so for the most part if you get hit more than once before getting to the Enemy Mega Men -- and that's 8 full boss fights to that point -- you're probably screwed. With such little room for error, suddenly the game's more abuseable techniques (Time Bomb, ZX spinning slash, ect.) don't seem so broken to spam.

* Wood Man is also particularly sour. He only has two attacks, but they combo into each other heavily. Wood Man's Leaf Shield is the mother of all HitboxDissonance, and is nearly impossible to jump over without a perfect running start. If you consider cheesing it with Item 1, the falling leaves put a hasty stop to that idea. The shield also blocks projectiles before Wood Man throws it (If only your own Leaf Shield could do that...), so it's hard to use his weakness of Atomic Fire while accounting for this. He's also weak to Air Shooter, but you're very unlikely to have it on hand at the point you first fight him as [[ScissorsCutsRock Air Man's only weakness is Leaf Shield.]], unless you actually bothered to read the manual, which suggested starting with Airman if you were a beginner.

* A battle with [[WolfpackBoss three]] level 3 Jammers happens during the endgame. They have above-average HP and fast attacks. While not too complex, they can overwhelm and quickly end you with their punches and machine guns if you make mistakes. If you die, you may even lose some progress because the battle happens [[DifficultySpike out of nowhere]] during a long period without Geo asking to save the game.

* The Yellow Devil from Wily Stage 1. Its difficulty stems from his attack pattern; he splits apart and flies across the room one piece at a time, and you have to have crazy good reflexes — or have to have memorized his pattern — to dodge him without getting hit. Once he's fully formed, his eye opens and fires a fast-moving projectile at you, then it closes and he starts flying across the room again. You only get a couple of seconds before the eye closes, and if you're trying to kill him with the Buster, the eye sometimes opens too high to hit. Not only that, but he takes forever and a day to die. And when he changes sides, you have much less reaction time to dodge with because he's already on screen, and less room to move.

* Wood Man is also particularly sour. He only has two attacks, but they combo into each other heavily. Wood Man's Leaf Shield is the mother of all HitboxDissonance, and is nearly impossible to jump over without a perfect running start. If you consider cheesing it with Item 1, the falling leaves put a hasty stop to that idea. The shield also blocks projectiles before Wood Man throws it (If only your own Leaf Shield could do that...), so it's hard to use his weakness of Atomic Fire while accounting for this. He's also weak to Air Shooter, but you're very unlikely to have it on hand at the point you first fight him as [[ScissorsCutsRock Air Man's only weakness is Leaf Shield.]]

* Doc Wood Man has a Leaf Shield with a significantly larger hitbox than that of the original to match his larger build--large enough that you'll need to either do a pixel-perfect leap over it, or use Rush Coil (which consequently [[MortonsFork smacks you into the leaves coming from above]]). The Leaf Shield also deals a whopping 8 damage, as does direct contact with Doc Wood himself, meaning that he can very easily take you out in just 4 hits. Just like Quick Man, trying to do a NoDamageRun on him is potentially nerve-wracking, as the mentioned precise timing takes a lot of practice (unless if you know how to use Rush Jet correctly, which is already a GameBreaker).

* The boss of the first Zero Space stage is the Shadow Devil, a traditional Devil boss from the Classic series turned UpToEleven. First, The Shadow Devil has ''six'' different random patterns it can go across the screen with instead of the usual one, and whenever it does, it leaves behind a green outline that if touched, if it doesn't OneHitKill you, it will leave you seriously hurting, greatly restricting your movement range. Secondly, the Shadow Devil can also randomly take the form of Wily Machine 6 at half health, trying to crush you as it moves across the screen. Thirdly, its weakness is Tri-Thunder as X and E-Blade as Zero[[note]]a direct ShoutOut to the very first Yellow Devil's weakness to the Thunder Beam[[/note]], but while X can shoot from a distance, Zero has to attack up close, making it very risky, and sometimes its eye can appear very high or low, only making damaging it even harder.

** The battle against the Gesellschaft takes this UpToEleven. You have to fight several Draches, the Gesellschaft itself, and then the HumongousMecha Focke-Wulf, one after another, with no continue points or opportunities to heal. You have to do it from the top of the Flutter, which is a small confined space and offers no defensive cover. The Flutter ''itself'' can take damage, there's no way of healing it, if it's shot down it's GameOver, and the ''enemies specifically target the Flutter over you''. You're also ''cut off'' from the town and any resources since the boss fight happens ''as you are leaving the dungeon and returning to town''. It is [[UnintentionallyUnwinnable technically possible]] to sabotage yourself so badly that you have no chance of winning, but fortunately even without being able to go back to town, they are very possible to take down by developing [[MoreDakka superior firepower]].

* Duo gets less fondly remembered compared to the other final bosses of the series, despite being largely on par with the other series final bosses. What makes his fight less favorable is how ''[[EarlyBirdBoss early]]'' it shows up compared to the other entries -- Counting postgame and all, Duo's first fight is in the first third of the game, compared to the other final bosses being fought around the two-thirds or three-quarters mark. This meant you had to make do with first-tier chips, and the Battlechip and Program Advance library in the fourth game was quite lackluster, just to make things more difficult. To rub it in, his back two columns are always empty, invalidating any chips that depend on striking a panel to do damage and further reducing the number of options the player has. Duo's fight feels fairer on subsequent playthroughs when the player has a more well-developed arsenal (like being able to access all six Souls), but the first round will be a pretty big hurdle to overcome.\\

* A battle with [[DualBoss three]] level 3 Jammers happens during the endgame. They have above-average HP and fast attacks. While not too complex, they can overwhelm and quickly end you with their punches and machine guns if you make mistakes. If you die, you may even lose some progress because the battle happens [[DifficultySpike out of nowhere]] during a long period without Geo asking to save the game.

* Acid Ace. He has a huge repertoire of moves, with something to break ''any'' Noise, and he doesn't follow a clear pattern with them. Then there's the matter of his R form, which is fought directly after Dread Joker R without a chance for you to heal.

{{Superboss}} is now banned from being ThatOneBoss. It's optional and you know it's overpowered; nothing prevents you from not fighting it. Examples from {{Game Mod}}s and {{Fan Game}}s are also banned, as they are unofficial and thusly have no standards for difficulty.

BonusBoss is now banned from being ThatOneBoss. It's optional and you know it's overpowered; nothing prevents you from not fighting it. Examples from {{Game Mod}}s and {{Fan Game}}s are also banned, as they are unofficial and thusly have no standards for difficulty.

* The Yellow Devil from Wily Stage 1. The Yellow Devil's difficulty stems from his attack pattern; he splits apart and flies across the room one piece at a time, and you have to have crazy good reflexes — or have to have memorized his pattern — to dodge him without getting hit. Once he's fully formed, his eye opens and fires a fast-moving projectile at you, then it closes and he starts flying across the room again. You only get a couple of seconds before the eye closes, and if you're trying to kill him with the Buster, the eye sometimes opens too high to hit. Not only that, but he takes forever and a day to die. And when he changes sides, you have much less reaction time to dodge with because he's already on screen, and less room to move.

* The Yellow Devil from Wily Stage 1. As lamented in [[https://www.youtube.com/watch?v=hN-YHyDrCdc& this song]], many gamers have lost a good chunk of their childhood trying to get past this shining example of NintendoHard. [[GoodBadBugs Unless they cheated.]] The Yellow Devil's difficulty stems from his attack pattern; he splits apart and flies across the room one piece at a time, and you have to have crazy good reflexes — or have to have memorized his pattern — to dodge him without getting hit. Once he's fully formed, his eye opens and fires a fast-moving projectile at you, then it closes and he starts flying across the room again. You only get a couple of seconds before the eye closes, and if you're trying to kill him with the Buster, the eye sometimes opens too high to hit. Not only that, but he takes forever and a day to die. And when he changes sides, you have much less reaction time to dodge with because he's already on screen, and less room to move.

* Doc Wood Man has a Leaf Shield with a significantly larger hitbox than that of the original to match his larger build--large enough that you'll need to either do a pixel-perfect leap over it, or use Rush Coil (which consequently [[MortonsFork smacks you into the leaves coming from above]]). The Leaf Shield also deals a whopping 8 damage, as does direct contact with Doc Wood himself, meaning that he can very easily take you out in just 4 hits. Just like Quick Man, trying to do a NoDamageRun on him is potentially nerve-wracking, as the mentioned precise timing takes a lot of practice.

BonusBoss is now banned from being ThatOneBoss. It's optional and you know it's overpowered; nothing prevents you from not fighting it.

** He is invincible at all times except when moving or attacking, moves like a spastic monkey on crack so that his vulnerability then doesn't even matter, and his attacks are irritating to dodge, because [[ShapedLikeItself Quick Boomerangs are really, REALLY fast moving]]. It doesn't help that he's the second boss of the game, the first boss was a complete chump, and the next boss AFTER him isn't exactly threatening either, so he's not even really a WakeUpCallBoss. Worse yet, it's ''entirely'' possible for the game to be UnwinnableByMistake here, as you can't leave his area (either to recover HP or improve your moveset) once you enter (but nothing stops saving...)

** The battle against the Gesellschaft takes this UpToEleven. You have to fight several Draches, the Gesellschaft itself, and then the HumongousMecha Focke-Wulf, one after another, with no continue points or opportunities to heal. You have to do it from the top of the Flutter, which is a small confined space and offers no defensive cover. The Flutter ''itself'' can take damage, there's no way of healing it, if it's shot down it's GameOver, and the ''enemies specifically target the Flutter over you''. You're also ''cut off'' from the town and any resources since the boss fight happens ''as you are leaving the dungeon and returning to town''. It is [[UnwinnableByInsanity technically possible]] to sabotage yourself so badly that you have no chance of winning, but fortunately even without being able to go back to town, they are very possible to take down by developing [[MoreDakka superior firepower]].

* The Yellow Devil from Wily Stage 1. As lamented in [[https://www.youtube.com/watch?v=hN-YHyDrCdc& this song]], many gamers have lost a good chunk of their childhood trying to get past this shining example of NintendoHard. Unless they cheated. The Yellow Devil's difficulty stems from his attack pattern; he splits apart and flies across the room one piece at a time, and you have to have crazy good reflexes — or have to have memorized his pattern — to dodge him without getting hit. Once he's fully formed, his eye opens and fires a fast-moving projectile at you, then it closes and he starts flying across the room again. You only get a couple of seconds before the eye closes, and if you're trying to kill him with the Buster, the eye sometimes opens too high to hit. Not only that, but he takes forever and a day to die. And when he changes sides, you have much less reaction time to dodge with because he's already on screen, and less room to move.

* Wily 4's boss, the Boobeam Trap, the five turrets with blindingly fast shots from the walls heading straight for you every five seconds or so. It's one of two bosses in the Wily Castle that is only vulnerable to one weapon, the Crash Bomber, which has a maximum of seven uses, and every single one (if you time it well, six) must be used to defeat both the turrets themselves and the destructible barriers protecting them. If you misuse a single shot, then [[UnwinnableByDesign you will not be able to defeat this boss]]. And since you don't get energy refills after death, you either need to take forever restocking energy off the few enemies in the pre-boss hallway or just GameOver entirely and restart the stage, [[ContinuingIsPainful which will strip you of all your E-Tanks]]. The only mercy you're given is that the barriers you destroy don't respawn if you die.

* Wily Capsule 7, the FinalBoss, is infamously difficult even by the standards of final bosses for the ''Mega Man'' series. His main attack is shooting four [[ElementalPowers elementally charged]] orbs that [[{{Roboteching}} stop mid-flight to adjust their path twice]], making them extremely difficult to avoid without great amounts of precision. While tbe electric sphere isn't a huge issue as it does minor damage and has no additional status effects, the ice sphere [[HarmlessFreezing freezes Mega Man in place, leaving him open to quick and powerful ground-traveling sparks for additional damage]], and the fire sphere immobiizes Mega Man and sets him ablaze as he takes a random amount of continuous damage. His weakness, the Wild Coil, is (as per the tradition) not only difficult to hit him with, but [[CountingBullets if even one shot is missed, it won't have enough energy to defeat him]]. [[WordOfGod Keiji Inafune, the franchise's producer, has admiited to purposefully making this fight insanely hard]], and even playtesters found this one impossible without using at least one E-Tank.

* Dynamo Man is a similarly brutal fight. His main attacks are dashing back and forth, deploying durable electric tendrils at three different heights, and jumping across the room while releasing five sparks in a semi-circle that dart towards the player [[RandomNumberGod in a random order]]. What really makes this battle particularly nasty are both that [[ShieldedCoreBoss a lot of his attacks shield him]], and his two {{Special Attack}}s. One is his Lightning Bolt, where he sends 3 orbs that orbit around him into the air and then brings down 3 fast, deadly sets of lightning strikes.[[note]]This attack can be prevented by shooting the orbs as they're circling him, but the timing is tight and they will quickly head towards the player after being shot.[[/note]] The other is [[TurnsRed when his health gets low]], in which case he will sometimes randomly jump into a recharger at the top of the screen and [[HealingFactor quickly regain health]] unless it's destroyed. Even his "weakness", Copy Vision, is a [[PowerUpLetDown pitiful stationary turret that does little damage to him and doesn't give him a special reaction]], making for a very hectic and drawn-out battle.

* Torch Man is an extremely intimidating opponent. He is a LightningBruiser, capable of unleashing ferocious fiery kicks at close range that require good reaction time to jump over, and quick [[{{Fireballs}} flaming fist projectiles]] from a distance that must be jumped over or slid under depending on their height. He's not afraid to follow up either with a devastating flaming dive tackle that homes in, hits hard, and will knock you away from him. Even getting away from him isn't safe, as he will quickly hop towards you to bridge the gap if you do. To make matters worse, when he [[TurnsRed reaches half health]], he gains access to the Power Gear, which gives him a DesperationAttack where he unleashes giant flaming wheels (that are ''very'' hard to jump over) from both sides of the screen one after another and finishes it off with a giant flaming column that once again tracks your position. Although his weakness, Tundra Storm, can make quick work of him, you'll have to be close to him to use it unless you use the weapon energy-guzzling Power Gear to make it a [[SmartBomb screen-clearing weapon]], and if you used all of it to freeze the OneHitKill [[AdvancingWallOfDoom Advancing Walls Of Doom]] in his stage, you're out of luck.

** [=QuickMan V2=] will likely be the first “ghost” boss Navi you fight (a stronger replica of the original that can employ new tactics and gives you a summon chip upon defeat, found on hidden squares in the net), showing up on the way to [=KotoSquare=] on a dead end path. Now he can use two boomerangs in rapid succession and, when he gets low on health, will zip over to your side to use a [=WideSword=]-esque move. Since you have to know in advance you’re going to fight him, you may not have saved, which can truly screw you if you’re just casually exploring the new area (plus his new tactics can leave you unprepared even if you had a good system on the first bout). Beat Quickman [=V2=] and you’ll have a chance of running into ''[=V3=]'' in the same zone (which could be as soon as completing same task that caused you to run into [=V2=]), who has even more HP and even ''more'' new strategies (among others his boomerang can now be thrown in a wave pattern, making it much harder to dodge).
* [=ThunderMan.EXE=] remains in the back row, and fields 3 thunder clouds that move back and forth the rows. These can fire off paralyzing thunder balls, and attack [=MegaMan=] if their movement gets obstructed. This results in the player needing to do some fancy footwork to be able to land hits on [=ThunderMan=] while dodging the clouds. And due to plot circumstances, the first time you fight him, you have also lost all your chips with exception to your folder, and you can't access the net to get new chips unless you beat him. In the Virtual Console rerelease, he has the potential to be ''even worse'' if the player has relied on the Gospel Breath chips (which can't hit anything in the back row) and hasn't upgraded the chip folder from time to time.

* You have to fight Bass twice in the storyline, though the first one is just a HopelessBossFight (you can't hurt him, and even you use something that makes you invincible, his attacks ignore it). The second fight, however, is a pain to get through, because he still has his Life Aura, and he attacks ridiculously hard, so it may take you a few tries if you don't have the right chip folder, and he comes right before you fight [[FinalBoss Alpha]], which if you lose to, you'll have to fight Bass AGAIN.

* Duo gets less fondly remembered compared to the other final bosses of the series, despite being largely on par with the other series final bosses. What makes his fight less favorable is how ''[[EarlyBirdBoss early]]'' it shows up compared to the other entries -- Counting postgame and all, Duo's first fight is in the first third of the game, compared to the other final bosses being fought around the two-thirds or three-quarters mark. This meant you had to make do with first-tier chips, and the Battlechip and Program Advance library in the fourth game was quite lackluster, just to make things more difficult. To rub it in, his back two columns are always empty, invalidating any chips that depend on striking a panel to do damage and further reducing the number of options the player has. Duo's fight feels more fair on subsequent playthroughs when the player has a more well-developed arsenal (like being able to access all six Souls), but the first round will be a pretty big hurdle to overcome.\\

* [=StarMan.EXE=] isn't one of the bosses that can shield your attacks, but he compensates that by teleporting around and floating out of range most of the time, not only that, but one of his two attacks involves dropping meteors diagonally on the screen, sometimes being even impossible to dodge and he LOVES to spam them, and every time he uses the attack he also teleports. It gets even worse when he's on low health, because he drops A LOT more meteors that fill most of the screen and are almost always undodgeable, and if anything he likes to spam them even more at this point.

* Le Mu is the greatest nightmare of the three Star Force Final Bosses, because the field is a storm of activity. In his first phase, Mega Man has to break open the seal down the front of Le Mu's chest, which is hard when Le Mu is launching giant drills out you, tearing open damaging portals all over the field, summoning Murian soldiers to attack you, or shooting at you with machineguns. Once you break open the seal on its chest, well, then things ''really'' get started. You still have to shoot at its core, but now it's moving around, attacking twice as fast and twice as hard, and it even has extra attacks, a pair of Big Fricking Swords and a WaveMotionGun! (Have fun!)
* Plesio Surf, because of all the irritating rocks he uses to block direct attack. It also prevents him from being bubbled by Cancer Bubble's attack, allowing for a super-devastating quadruple damage Elec-element combo (water terrain double damage + bubble double damage). Although, one could argue that this was the programmers' way of leveling the playing field to keep the fight from being too one-sided. Still, it's annoying as heck, especially when you need to beat it fast enough to qualify for its strongest Mega Card.
* Yeti Blizzard can compete with Le Mu itself in term of activities you need to watch out for. Good luck dodging the snow ball that only left you one square free, the stomp that you can't block and the ultimate attack that become a ''Giga'' cards.

* Although the Crimson Dragon is considered one of the easier bosses in the franchise, the sheer amount of activity on screen can be stunning for newer players. You're always attacking, dodging, or blocking, with little to no breathing room in between. He also has the annoying mechanic of having to destroy his head every once in a while (recycled from Battle Network's Alpha) to damage the core, which can end up soaking an extra 800 or so damage over the course of the fight. His Sigma version drives this up even further with an even larger health pool and even faster attacks, making it hard to get an attack in without recovery chips and Super Armor.

* Wily Machine #2, the penultimate boss battle, is considered to be a pretty tough battle by most people. First of all, all of the projectiles that Wily fires deals 6 damage while contact deals 10 damage. It's hard to dodge a lot of the projectiles and during the second phase, you ''will'' get damaged unless if you use a well-timed Crash Bomb as the second form is loading up (which can possibly instantly destroy it before the phase even starts) - but good luck considering you'll most probably be out of Crash Bombs thanks to the Boobeam Team, either forcing you to manage your Crash Bombs even more (which is possible) or get a game over have to fight the other bosses all over again.

* Wily 4's boss, the Boobeam Trap, the five turrets with blindingly fast shots from the walls heading straight for you every five seconds or so. It's one of two bosses in the Wily Castle that is only vulnerable to one weapon, the Crash Bomber, which has a maximum of seven uses, and every single one must be used to defeat both the turrets themselves and the destructible barriers protecting them. If you misuse a single shot, then [[UnwinnableByDesign you will not be able to defeat this boss]]. And since you don't get energy refills after death, you either need to take forever restocking energy off the few enemies in the pre-boss hallway or just GameOver entirely and restart the stage, [[ContinuingIsPainful which will strip you of all your E-Tanks]]. The only mercy you're given is that the barriers you destroy don't respawn if you die.

* Doc Quick Man is just as fast and unpredictable as the original, but is also [[LightningBruiser larger and more resilient]]. He also deals far more CollisionDamage (8, as opposed to the original's 4), and due to the way that he runs and jumps all over the place, it's extremely difficult to avoid bumping into him. This is such a deadly threat that a common strategy is to get hit by his Quick Boomerangs ''on purpose''; they deal far less damage, and the resulting MercyInvincibility can be used to avoid a devastating collision.
* Doc Wood Man has a Leaf Shield with a significantly larger hitbox than that of the original to match his larger build--large enough that you'll need to either do a pixel-perfect leap over it, or use Rush Coil (which consequently [[MortonsFork smacks you into the leaves coming from above]]). The Leaf Shield also deals a whopping 8 damage, as does direct contact with Doc Wood himself, meaning that he can very easily take you out in just 4 hits.