Contested Sequel: The original Guardian Heroes was a Cult Classic that everyone cherished but few played until the Updated Re Release on Xbox 360, where it was lavished with further praise. Advance Guardian Heroes on the other hand had to make itself to the Game Boy Advance, so some downgrades were understandable, but the product as a whole has been maligned and praised alike for being almost nothing like its predecessor.
Difficulty Spike: Depending on the path you take, the later stages of the game can go from manageable to chaotically difficult when you have six or more foes bum-rushing you.
Randy in the original game seems like he'd be a bit of a Squishy Wizard, and indeed his vitality isn't the highest. But take care with managing his MP, and he'll be able to shut down entire battles singlehandedly, faster and harder than even the Golden Warrior can keep up with.
In Advance Guardian Heroes, Dylan, arguably. His down-aerial sends him tumbling down toward the ground and landing with columns of flame shooting up around him. It has one of the highest priorities in the game, renders him effectively invincible until it finishes due to that priority short of perhaps the final boss's auto-stun eye, and does reasonable damage in a fairly wide area as well. His down-ground attack is a spinning leg kick with lots of knockback, decent damage, and also has high priority. His side-ground attack is a bit slow starting up, but does a lot of damage, and also stuns the target momentarily like a lightning spell does. His stats are well-rounded, and his lightning spellbook is nothing to laugh at either. This kid's in-story performance does not do him justice.
Good Bad Bugs: In the Saturn version of Guardian Heroes, it's possible to start a new game on Easy, quit, switch the difficulty to Hard and then resume playing the game on Hard mode with 99 continues.
Lethal Joke Character: Nicole Neil in Advance Guardian Heroes. Looks like a magical girl but with more smilies, has some rather silly voice clips, shoots smiley faces at people. She's also the only character to have a long-ranged, piercing basic attack (side-ground, any direction in the air), her basic ground combo inflicts all the elemental status effects in sequence, and her stats start out perfect for shielding and counters, which is helped more by her down-ground attack being a larger shield with damage and knockback, and her lone spell setting up a regeneration zone if used while on the ground. Her only real weakness is that she's really, really slow.
Most Wonderful Sound: The *schwing* noise that plays when scoring a counter in the sequel.
Polished Port: The HD re-release on Xbox 360 has (optional) HD graphics, an improved English script, online co-op, a bigger Versus Mode for up to 12 players, and a Remix mode that completely changes how the game is played.
Scrappy Mechanic: It shouldn't be enough to usually botch most playthroughs, but the game has an invisible Karma Meter that hates it if you play "immorally". As in, destroying too many objects, attacking fleeing enemies or civilians, and juggling dead foes. Just playing the game regularly should be able to avoid getting the darker endings, but if fights get too clustered — and they will — it can be way too easy to rack up the bad karma, especially if the Golden Warrior is on attack mode where he will just infinite-juggle with impunity if given the chance.
The final boss' flamethrower in Advance Guardian Heroes. Get hit even once, and the rest of the attack will completely annihilate your health meter. His full screen stunning attack during the final phase also amounts to a One-Hit Kill if it isn't blocked, so don't get impatient.
Kanon's Ice Circle in the original game. He'll spam it repeatedly, killing you before you can even move.
Woolseyism: The XBLA re-release's script is a marked improvement over the original game, with plenty of humor and creative wordplay.
from the original Saturn game. It even made it into Advance Guardian Heroes as the music you hear when battling the other heroes.