I also failed to find it online by searching the things I remember. the game was an edgy, bloody side-scroller, where you need to shoot through levels of whimsical creatures, and the 4 main villains were heroes from other platformer games. the only two I remember are Rayman and Mario. I was an elementary school kid, and I remember that game vividly, but I couldn't read English back then and I don't remember much else. I thought a game where Rayman is the villain would be easy to find, but I can't find anything myself.
thank you in advance, i hope this was the subreddit to post this.
Source: https://www.reddit.com/r/oldgames/comments/w445ta/old_game_i_remember_playing_but_dont_remember_the/