History NewPowersAsThePlotDemands / AnimeAndManga

** Being MerchandiseDriven, this often happens with brand new cards just revealed, and often these cards are A) highly situational to the point in any real deck they'd be dead weight, and B) never seen again after their one usage. On occasion the new card that is used is a real life card that they just didn't use in the show before (such as Skilled Dark Magician), other times the card is completely made up with powers verging on GameBreaker levels (such as ''the entire Orichalcos archetype''). A fine example of this is [[https://yugioh.wikia.com/wiki/Xyz_Dimension_Splash_(anime) Xyz Dimension Splash]] - a card that can only be activated when banished facedown by an opponent ([[DeaderThanDead banishing effects]] are generally not something you waste on random facedowns), and has an effect that would only be useful to someone playing a Rank 8 deck, when it was used by Shark, whose deck is focused on Ranks 3-5. Conveniently, he drew it when facing an opponent who had a mass-banishing effect, while tag-teamed with an ally who used Rank 8s heavily.

** The innate ability to sense energy is meant to be quite rare in DBZ, hence why Frieza's entire army (and even Frieza himself) utilize scouter devices. Vegeta relied on a scouter when we first meet him - although he knew not to trust them entirely - yet by the Namek Saga he randomly gained the ability to sense energy all on his own. With the Ki sensing, however, it wasn't that Frieza and his minions couldn't do it, but they didn't know that it even could be done. Vegeta mentioned that after he found out it was possible, he easily taught himself the ability. However, he isn't as good at it compare to the Earthlings. In ''Super'', he learns Super Saiyan Blue off-screen by training with Whis and, unlike Goku, he gained god energy without the ritual.

* ''Literature/ACertainMagicalIndex[=/=]Manga/ACertainScientificRailgun'': Played for laughs with Gunha Sogiita. Since no one--including him--[[HowDoIShotWeb has any idea how his powers work]], he seemingly just makes up new ones whenever he encounters a problem. His basic power appears to be some sort of energy field that enhances his strength, endurance, and speed. Other demonstrated powers: A hefty HealingFactor in the rare instance he gets injured, some sort of invisible BarrierWarrior power with the side effect of rebounding the damage on himself, suddenly gaining DishingOutDirt powers when facing an electric esper because "[[ElementalRockPaperScissors electricity is weak to earth, right?]]", and randomly becoming ImmuneToMindControl when Misaki Shoukuhou paralyzed him.

* In ''Anime/ChargemanKen'', Ken uses new powers with zero explanation. At one point, he uses super-hearing to detect a ticking in a professor's head. He deduces the professor is a robot clone and that the ticking is dynamite in his head.

* ''Manga/AttackOnTitan'': Eren's [[spoiler:Titan Shifter abilities (all of them)]] progressively manifest when he desperately needs them. Of course he is [[{{Handwave}} set up]] as suffering memory loss and nobody is telling him [[HowDoIShotWeb how any of this works]]. Uncertainty and not knowing just about anything is a common recurring element in the story. For example, when Eren and Mikasa are faced with the Smiling Titan while separated from their allies and unable to escape, Eren awakens the ability to [[spoiler:control the mindless Titans and have them eat the Smiling Titan.]] It later turns out that there's a justification for this- [[spoiler:the Smiling Titan is Eren's stepmother Dina, a member of the royal line, and her bloodline awakened Eren's Coordinate ability.]]

** Dio Brando invents a new power every time he's on screen, with the excuse being that [[OurVampiresAreDifferent Vampirism]] gives him complete control over his body in ways that JoJo can't even imagine. In addition to stock vampire abilities like super strength and speed, he can also levitate, create zombies, enchant people, mix and match body parts, stop blood circulation so hard that he can flash freeze humans, teleport in the anime, and shoot high pressure blood out of his eyes so quickly that it's essentially a laser. Oh and in Part 3, he displays the ability to manifest "flesh buds" that give him psychic control over his underlings and will mutate once he's dead.

*** In the first example, we have Itachi Uchiha who in his battle against Sasuke showed such ability as [[InstantArmor Susanoo]] which in principle is some sort of giant spirit robot which wields 2 of Japan's Sacred Treasures: the Totsuka Sword (Evidently another version of the Kusanagi) which here is a LaserBlade with sealing abilities, and the Yata Mirror which functions as a shield able to protect against anything. All this appeared directly out of nowhere and needed only in order to seal Orochimaru and give Sasuke in the future the same ability. And also later in the battle with Kabuto, Itachi will show such jutsu as Izanami, the purpose of which is incredibly contrived and wouldn't have worked on anyone except than the person Itachi was fighting at the time.

*** And in the last example [[spoiler:Obito Uchiha]] apparently following the general tradition his clan, showed a new ability out of nowhere. [[spoiler:After his death he reverts to his younger self and immediately uses his shiny new Mangekyo Sharingans to teleport back to the world of the living, where he using chakra transfer transfers his eyes to Kakashi, stronger than they ever were when Obito was alive.]]

** Scar displays a rather odd power during an episode of [[Anime/FullmetalAlchemist the 2003 anime version]]. Trying to find out where the Elric brothers are, he places his arm on a stack of their research papers, and gathers all the words into, what can only be called, a knowledge ball. [[BigLippedAlligatorMoment This ability is never mentioned beforehand, and never spoken of after the scene]].

* ''Manga/AttackOnTitan'' Eren's [[spoiler:Titan Shifter abilities (all of them)]] progressively manifest when he desperately needs them. Of course he is [[{{Handwave}} set up]] as suffering memory loss and nobody is telling him [[HowDoIShotWeb how any of this works]]. Uncertainty and not knowing just about anything is a common recurring element in the story. For example, when Eren and Mikasa are faced with the Smiling Titan while separated from their allies and unable to escape, Eren awakens the ability to [[spoiler:control the mindless Titans and have them eat the Smiling Titan.]] It later turns out that there's a justification for this- [[spoiler:the Smiling Titan is Eren's stepmother Dina, a member of the royal line, and her bloodline awakened Eren's Coordinate ability.]]

** In the [[{{Filler}} Invasion]] [[{{Anime}} Arc]]. the villain's zanpakutou is this. [[FillerVillain Kageroza's]] zanpakutou has the power to manipulate space/time. Then it's revealed to have the power to teleport and duplicate. Then it has the power to resurrect "dead" reigai. Then, when Ichigo is about to defeat the villain, his zanpakutou is revealed to have a cloning ability. The apparent damsel of the arc, [[CreatorsPet Nozomi]]'s zanpakutou has the power to drain reiatsu. Then it's revealed to be able absorb the attacks of anything thrown at it, combine it with her own power and throw it back as a more powerful attack. Then it's revealed that Kageroza's and Nozomi's power are two halves of the same original zanpakutou and, when recombined, the zanpakutou gains all the powers in combination which suddenly results in the power to destroy the entirety of Soul Society with a single activation command. And, somehow, the original zanpakutou never had any of these abilities at all until the owner, fed up with being treated as weak, turned evil and decided to obtain more power by splitting himself in two and recombining himself (how this makes him more powerful and gives him powers he never previously possessed is never explained).

*** Hilariously, ''Anime/HappinessChargePrettyCure'' runs with it. Megumi, after transforming into Cure Lovely for the first time, is told that she doesn't have set attacks and just make stuff up. She runs with it.

* ''Manga/InazumaEleven'' anime develops itself into this. At first, many skills the team learn come from books and manuals, but by the third season, characters repeatly pull out new things whenever the plot demands them. In the movie, the protagonists learn to use super power abilities without any explaination just so they can beat the Ogre, who's argubly stronger than the series' world cup teams.

* Spoofed in the fifth episode of ''Anime/TigerAndBunny''. When Wild Tiger and Barnaby are in a pinch and [[HourOfPower almost out of time]], their PoweredArmor automatically switches to the the brand new Good Luck mode Saito installed and they manage to incapacitate their opponent just before the clock runs out. So what does Good Luck Mode actually do?
-->'''Barnaby:''' So this new mode increases our power?\\

** The Winged Dragon of Ra is clearly this, revealing a new secret ability ''every single time'' it gets played. A full list of its abilities: its ATK and DEF are equal to the ATK and DEF of the monsters tributed to summon it, you can pay all but 1 Life Point to increase its attack by the same amount, you can pay 1000 Life Points to destroy a monster on the opponent's field, and you can tribute other monsters to add their ATK to Ra's ATK. And that doesn't count the requirement one needs to have Ancient Egyptian heritage and has to recite an ancient chant in order to summon it, and the immunity to card effects it shares with the other god cards. And the aforementioned effect to pay life points and increase Ra's attack? It can be reversed, allowing the user to to take back all of those attack points as life points by using ''De-Fusion''.
** Spoofed mercilessly ([[AffectionateParody along with everything else]]) in ''WebVideo/YuGiOhTheAbridgedSeries''.
--->"Conveniently, my Millennium Puzzle allows me to put souls back into their original bodies!"\\
"I activate a spell that allows our monsters to trade places! Which would be completely useless in any other situation."\\
"I have placed a part of my soul inside the Millennium Puzzle, because apparently I can do that."\\
"Now I shall use Mega-Ultra Chicken's secret ability that I just this second made up to convert my Life Points into Attack Points, merging me with the beast itself!"

** ''Naruto'' is so symptomatic with this trope that the fandom has its own [[FanNickname nickname]] for this kind of revelation, "[[AssPull Plot No Jutsu]]".

* For nearly a hundred episodes in ''Manga/YuYuHakusho'' the audience has know Kurama to be a [[GreenThumb plant user]]. But in the fight against [[spoiler: The Elder Toguro]], he used a smoke screen? Where'd that come from?

* ''Manga/DetectiveConan'': Conan can do anything. ANYTHING. He can drive a car, scuba dive, shoot a gun, drive a boat, drive a Jetski, fly a small plane, and FLY A HELICOPTER (which is completely different from flying a plane). Why can he do these things? Because he "learned in Hawaii!"
** The knowledge of flying a helicopter is handwaved as him using a simulator at a local science center "when he was a kid" (which is still probably ''very'' different than flying an actual helicopter), which gets the rather amusing response from Kogoro of "You still are a kid!"

* ''Franchise/PrettyCure'':

* Quite common in ''Anime/{{Pokemon}}'', although mildly justified based on the source material. However, an unusual variant of this trope also appears, in that Pokemon which Ash has ''never used before'' often turn out to be inordinately strong. One of the best examples of this is the Indigo League arc of the original Johto season; Ash's never-used-before Muk basically helps Ash sweep his way all the way up to the final match, whilst his likewise previously unused [[GiantEnemyCrab Krabby]] not only won its very first battle on the field, but promptly turned into the even more powerful Kingler.

** [[SlimeGirl Suu]], being one of the few cast members based on a modern monster rather than a mythological one, tends to manifest new abilities whenever the plot requires it, with it being {{lampshaded}} that there's really not a lot of info on how slimes work. Most egregiously, at one point it's revealed that she's capable of reading minds.

* In ''VideoGame/Persona5TheAnimation'', Ren suddenly becomes able to use Fusion midway through the fight with Shadow Kamoshida, when all hope seems lost. He then fuses Arsene, his initial Persona, with Pixie, the only other one he possesses, to form Agathion(which ''is'' the actual result of the fusion in game), and manages to easily defeat Shadow Kamoshida despite Agathion having a base level of 3 in-game.

** Zoro activats a brand-new nine-sword-style god form during his fight with Kaku. The closest thing to an explanation came over '''500''' chapters later during the Wano Arc, where [[spoiler:the Emperor Kaido believes it's a manifestation of [[AwesomenessIsAForce Conqueror King's Haki]]]].