don't even mention the fact that it just doesn't make sense for some 6 year old boy, a highly trained space soldier, a fantasy knight, and literally a pink amoeba (with the ability to create immense pressure difference) to fight eachother, like, there's a massive weight class, size, combat skill, etc. difference between all of them
plus, since they all come from various different game universes in the first place, it's fairly obvious that SSB isn't canonical by any means and is more of a "what if" kind of thing for fun