There was an old PS2 fighting game that just threw together a bunch of characters from other fighting games. You could pick 2 characters at a time to play with, and it worked like "Marvel vs Capcom" in a lot of ways, like switching between characters, switching between movesets, and extremely powerful moves fueled by some bar
All I remember of the characters were Ryu, Felicia (Played her because of the bewbs, why else?), some vampire looking guy, and a motherloving T-Rex