Guardians

Guardians/Denjin Makai II is an obscure Japan-only beat'em-up released in 1995 by Banpresto (i.e. those guys who made all those robot games). While the graphics and sound weren't that special at the time, and the story is basically nonexistent as can be expected for the genre, its main claim to fame is 8 distinctly different playable characters, each with a large moveset: each character has 4 basic combo strings, a projectile attack, 2 different Desperation Attacks, 2 basic special attacks, a Limit Break and a varying number of unlisted special attacks.

The characters are as follows:

Zeldia/Zel Dia, a female Winged Humanoid with claws.
Jinrei, a Ninja.
Skullbyule, Mix And Match Critter consisting mostly of insect features.
Girulian, a martial artist with a focus on kicks and some unorthodox moves. Final Boss of the original Denjin Makai.
Kurokishi, a Kick Chick.
Rou, a Kung Fu Wizard.
Tulks, a wrestler.
P.Belva, a robot.

Tropes used in Guardians include:

BFG: P.Belva gains one for his power desperation attack.
Bonus Stage: In preset points of the game, you use your character's projectile attack to shoot down large amounts of enemies from a third person viewpoint.
Cast From HP: Unlike in other BeatEmUps, normal desperation moves don't cost any life and instead use the Power meter like all other special attack, but to compensate, they don't generally have much range or do that much damage. Played straight with the stronger variation that have a much larger range (either a large area in front of or around the character or the entire width of the screen in front of the character) that kill most normal enemies in a single hit and do a ton of damage to bosses, but cost 1/3rd of your lifebar to perform.
Chest Blaster: Skullbyule's power desperation attack.
Combos: Tons of them. Most characters can freely juggle hopeless enemies back and forth as much as they please, although to limit this, generally you can only use each move once after the enemy leaves the ground and any further attempts pass through them harmlessly. Most of them are Awesome but Impractical since after 10 hits, most additional hits do no damage to the enemy. They do give you a nice score bonus at the end of the stage if you care about it though.
Counter Attack: Useable by everyone, can lead to combos if timed correctly.
Death in All Directions: Skullbyule's air power desperation attack.
Eye Beams: Girulian's basic projectile.
Face Heel Turn: Girulian will do so sometime after the end of this game, as he serves as the last boss in the original Denjin Makai.
Hurricane Kick: Kurokishi's normal desperation attack and Girulian's horizontal basic special attack.
Kamehame Hadoken: Rou's power desperation attack, although his version involves the aid of a pair of metal spheres, which he charges with electricity beforehand.
Limit Break: Usable by making the character's name flash (which is in turn accomplished by getting lowered to red health or hitting enough enemies to make all segments of your Power bar to light up) beforehand and then using a specific command. Results vary from extended combos to projectile spam.
Mascot Mook: The strange one-eyed octopus that pops up at seemingly random spots during stages and flies away soon afterwards. There's also a random chance that he replaces your hoverboard (which you normally use to position your character after losing a life), allowing you to briefly ride him.
Offhand Backhand: P.Belva's back attack.
Prequel
Rocket Punch: P.Belva, as can be expected: his fist doesn't detach though, and it's closer to using his rocket boosters to allow him to punch the enemy extra hard. He does appear to perform one in the intro animation though.
Rolling Attack: Skullbyule's dashing normal attack.
Shoryuken: Everyone except Skullbyule and Tulks use some kind of a variation of this as their upward basic special attacks.
Some Dexterity Required: Thankfully averted: while the move input method for general special attacks is somewhat unorthodox (hold down the attack button and input directions), the directional inputs are never longer than 4 button presses and you can input them as slowly as you want.
Spam Attack: P.Belva's basic horizonal special attack.
Spin Attack: Most basic desperation attacks.