I agree with metal. He does know what he speaks of. But I do agree with Arcadenik. Metal, you have to think about how additions work. For example, adding generation 5 pkmn instead of generation 1 pkmn would make players happer. In otherwords Sandslash<Zoroark, for example.
But the thing I disagree with Arcadenik is the addition of characters, like Dr. Mario, having no gain. Bro, you must be nuts if you think that. Otherwise, no one would bother voting for him to come back. Just logic sense, really. Look at SSBF's poll. Mewtwo has a HUGE advatage on everyone (last time I checked). Popularity always goes first, but revelance is important, too. Ghiriam (LoZ Skyward, dunno how to spell his name), and Victini (Pokemon) are two great examples. Also, it's common knowledge that this game will stay with the future. Sakurai wouldn't rail SSB4 by fusing 1, 2, and 3 to make a game.