Regarding Mewtwo, I have to wonder if they'll bring him back or use the new Mew Pokemon. People think it's a new form, but I honestly don't think it is, especially when it's set to appear with Mewtwo in the upcoming movie and how they keep saying "A new Pokemon with a familiar look" and when it came to it being completely related to Mewtwo or being the same they finish with "but not quite"
I'm guessing this is a new experiment by Team Rocket to succeed Mewtwo. Another theory is that it's a female clone of Mew. Mewtwo looks very masculine and we can all agree he's "male". This new Pokemon looks feminine and more nimble and petite. Not sure how I would feel if this Pokemon would take Mewtwo's potential spot in the roster. Then again, Smash 4 is bound to have DLC, and I can totally see Mewtwo's moveset differentiating itself from this new Pokemon when you take their builds into consideration. Mewtwo would probably have to be heavier in Smash 4 and this new Mew would be lighter than him. Many possibilities. Lucario can stay since he's still popular with a lot of people. I don't think anyone will get cut as there is no reason to do so. Roy might make a return with his new look from Awakening. Krom is bound to represent Awakening as well. So we'd have 4 FE characters which is fair. I'd like the 5th to be Lucina or Lyn, just so we can have one female rep for the series.
Kid Icarus needs Hades, Palutena and/or Medusa. Anyone who's seen the short anime featuring Palutena can see she can be a capable fighter with the magic and skills she possess. Even in Uprising. I would have thought Magnus would be great for Smash 4 but I'm not sure if he's as significant as Hades and Medusa. If they could, I would love Phosphora to be added as well but it may be too much... Sakurai will eventually have to come forward and mention DLC- whether it's going to happen or not. He hinted it for Brawl that if the Wii could, there was a possibility. And as for people worrying about balancing, because Namco Bandai is handling the mechanics of the game (but mostly the engine- graphics, sound, etc), I would think they'd initiate patches to balance characters out accordingly. So, having too many characters and fearing balancing issues should be in the back of everyone's minds if they follow through with such things.
Whew, I'm going off on a tangent. Sorries. This new Mew thing has me excited not only for Pokemon XY but Smash Bros...