Fighters Megamix

Sega's own Massive Multiplayer Crossover Intercontinuity Crossover, originally developed by Sega's AM2 development team as a Crossover between Virtua Fighter 2 and the first Fighting Vipers.

The characters roster is the following:

Virtua Fighter: Akira, Lau, Pai, Wolf, Kage-Maru, Jeffery, Sarah, Jacky, Shun, Lion, Dural, Kid Akira and Kid Sarah.
Fighting Vipers: Bahn, Grace, Sanman, Honey, Jane. Raxel, Tokio, Sanman, Picky, Mahler, B. M. and Kumachan.
From other games: Janet, Rent-A-Hero, Bean and Bark and Hornet.
Introduced in this game: URA Bahn, Siba, Deku, Mr. Meat and Palm Tree.

All the stages and characters from both games were included as well. Some of the changes included the Virtua Fighter 2 stages no longer being rings, the Virtua Fighter 2 characters's movesets updated with moves from Virtua Fighter 3, and the Fighting Vipers characters given new moves (evne if their armor can still be broken)

As crazy as this game and it's roster was, it was great because it was 100% grade A Guilty Pleasures.

See also Sega Superstars, a later Sega crossover series. Compare with Dream Mix TV World Fighters, another over-looked 3D fighting game with wacky characters.

Tropes used in Fighters Megamix include:

Anime Hair: Akira and Jacky.
Ass Kicks You: Honey and Sanman.
Button Mashing: Bean's cheap peck of death.
Canon Foreigner: Siba, Deku, Mr. Meat and URA Bahn.
Car Fu: Hornet, literally!
Chef of Iron: Lau.
Chrome Champion: Dural.
Clothing Damage: Breakable armor on some characters.
Combos
The Computer Is a Cheating Bastard
Crossover: Aside from being a crossover of Virtua Fighter 2 and Fighting Vipers, various other characters from AM2's other arcade games make an appearance, and features music from other games whose characters don't make an appearance.
Ditto Fighter: Dural.
Drunken Boxing: Shun.
Drunken Master: Shun.
Facial Markings: Wolf.
Hot-Blooded: Akira.
Lethal Joke Character: Deku, Bean and Kumachan.
Mighty Glacier: Wolf, Jeffery and Sanman.
Ninja: Kage-Maru.
Noblewoman's Laugh: Sarah.
Old Master: Lau and Shun.
Stripperiffic: Grace and Honey wear next to nothing when their armor breaks off.
Super-Deformed: Kid Akira and Kid Sarah.
Suspiciously Similar Substitute: Janet, who has many moves from Virtua Fighter 3's Aoi Umenokouji.
Victory Pose
The Voiceless: Dural.
Wrestler in All of Us: Wolf.