These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Demonic Spider: Mark is a surprisingly formidable Mook, who likes to spam his charging shoulder rush move that flings you across the stage and effectively renders him immune to close-range attacks (unless you manage to get him from behind) and takes a lot more damage than other mooks up to that point.
Knights are even worse, requiring that they be hit twice in rapid succession before they even take damage (the Final Boss is the only other character that does this.) The only real tradeoff is that they have no special attacks.
Game Breaker - Henry + Beer = Sonata of Death until you die. To elaborate, Sonata of Death levitates sufficiently close enemies into the air so they are helpless while damaging them. Beer quickly restores MP to use it again. When Sonata of Death ends, the players hit with it fall to the ground and must wait a few seconds to get up. As long as Henry has MP, players hit by Sonata of Death are effectively helpless.
Julian, who has a powerful basic attacks, an armor that lets him get hit twice before taking any real damage, an easily spammable attack that fires multiple skull like projectiles with minor tracking ability, a powerful and large projectile that can overpower multiple weaker projectiles and a move that's basically an explosion of energy around him. All of those moves have a very low cost compared to their damage output. Oh, and on top of that he's pretty fast.
Firzen, who's one of the fastest characters in the game, has a shield that can reflect projectiles, a move that fires a powerful beam of energy, a move that fires at least 4 (depending on the number of opponents) homing fireballs and ice balls into the air which can knock you into each other as they land (and if it happens when he spams it, you're dead) and a move that's that plus an explosion of fire and ice around him, which is a potential One-Hit KO if you're next to him(and the ice balls can freeze you, so he can easily move next to you and use it).
Oh, and while he's readying the explosion, he doesn't flinch. All you can do is just run the hell away and pray you don't get caught in it.
The last two can also count as SNK Bosses when encountered in Stage Mode, easily annihilating whole armies in a matter of minutes.
And if you thought those two weren't already enough of a Game Breaker, try the secret character Conrad from LF2 Reinforced. With multiple hell movesnote To further clarify, in R-LF 2 (Reinforced Little Fighter 2) every character, even the Mooks have all their attacks powered up, and are given a unique (and potentially) game-breaking technique called "Hell Moves". CL (or Conrad as some others call him) doesn't have a Hell Move, he has MULTIPLE, one that summons an evil sword, another to summon a dark dragon which effortlessly charges through enemies (and charges more than once!), one that removes a character from the match, and one that shoots multiple HOMING projectiles that trap an enemy in a column of dark energy UNTIL THEY DIE., Mercy Invincibility when hit, much higher HP and MP regeneration, and special moves that do some crazy damage, Conrad makes Julian look like a joke in comparison!
No one ever mention Firce777? He's probably the most broken mod character. He shoots a wave of fireballs and wave of iceballs in front of and behind him respectively, while standing. He shoots a wave of arrows, explodes and spawn tornadoes when walking. He can also spawn five Firzens as well as five energy discs and increase his mana by a little bit (the creator names this move "Five Loaves Two Fish"). And for the worst part? He can turn invisible for free and cause his Firzens turn invisible as well.
Freeze's projectile was the single best non-boss projectile in the game before it was eventually Nerfed, not only able to freeze enemies, but also reflect projectiles while converting them into ice projectiles as well.
Sequel Displacement: How many people who've played the game would even remember that there's a game before it if not for the 2 in the title?