everyone pretty much named the best of the best. All the konami and any capcom games are usually ace. I personally own Turtles and Turtles in Time and i must say 4player rounds of that are pretty intense.
There is some kind of fantasy style beat em up out there with 4+ players. I thought it was Golden Axe, but I was wrong. OK, just looked it up, and it looks like there were a couple of Dungeons & Dragons: Tower of Doom & Shadow Over Mystara. And it's made by Capcom, so it's pretty darn good. Oh yeah. Gauntlet is also a good…