Since Donkey Kong and Metroid are getting new games, I wouldn't be surprised if we actually got K Rool and Ridley in the next game.
Especially considering he's gotten some real roids and looks pretty humanoid now. =P Seriously, I'm LIKING the heavyweight look they gave him though. He looks even more intimidating.
Jokes aside. I think F-Zero, Earthbound, Kirby, and StarFox have enough representation.
F-Zero and StarFox appear to be a little dead at the moment-- Maybe forever, maybe not. And yes, I know StarFox is getting a port to the 3DS, but I don't count that. If I counted ports, I'd say we already have SSB4.
Kirby doesn't really need more, StarFox doesn't really need more, Earthbound does not need as many characters as it has GAMES... I mean really, what. We have the protagonists for all of the mother games already, and Giygas isn't...... Uhh... physically possible. So, unless they add like, the villain of M3, then I doubt we'll get more.
Mario is good to go, unless they decide to throw in Bowser Jr. or something. If that happens, odds are Pokemon and LoZ will get another slot too.
Has Yoshi even had a new game recently? And I don't mean Galaxy 2. Like, a Yoshi's Island game or whatevs.
Fire Emblem could bring back Roy and then we'd be good... Unless they want to toss Ashnard or the Black Knight or SOMETHING in there from the newer games... I know nothing of new Fire Emblem. =P
G&W, Gyromite, Ice Climber... were made with one rep in mind...
Kid Icarus I bet will get one rep, either Palutena or Medusa. I hope for Medusa, smash should have more villains.
Did I cover all of the series? Uhm... Mario, StarFox, Kirby, Yoshi's Island, Metroid, F-Zero, Pokemon, Earthbound, Donkey Kong, LoZ, Fire Emblem, Ice Climber, G&W, Gyromite...
WarioWare, I got nothing. I know nothing about the series...
For Metal Gear and Sonic, I think we'll keep our current two, but not get any newcomers in the series. However, we may or may not get another 3rd party.
So if it's a case of tl;dr, basically, DK, Metroid, Yoshi,Kid Icarus, and Fire Emblem are the only series that COULD have room left possibly in their part of the roster. The others are either dead, or not intended to have more than one rep.
Speaking of Galaxy 2, I started playing it. It's fun. =P Yay lack of spoilers from the internet!
EDIT: I had made a moveset for Twilight Princess skullkid, I remember. It was for MYM, I dunno where the forum or the moveset are now. I will link it when I find it some time.