Board Thread:General Discussion/@comment-4383275-20150824053458/@comment-7424710-20151019150428

Actually, it is fair. Unless these characters are met with a certain requirement (Mario with Golden Tanooki and Luigi given the usual Mario powerups), they lose fair and square.

Think of this as the base characters. For example, base Wario kills Knuckles. But if Knux meets a certain requirement (aka Super/Hyper Knuckles), then he would win. It's all situational.