Since Mewtwo already has a trophy, I fear that the other DLC characters are hidden in the trophy list as well... Rayman is very possible to me. Rayman (and some of his friends) in the trophies is very odd, I think he will be a DLC character along with Mewtwo.
I think that Kirby will have a 4th rep for almost sure.
At this point, I think, if Bandana Dee has not a trophy, that the most possible characters are Magolor and Galacta Knight (not another Dark Pit -.- at least he has a shield and a lance, maybe he won't be a direct clone to MetaKnight); now, I honestly think that Magolor is very possible (not a fan of him, I think that the Kirby series has more or less a new final boss each new game, and taking just one of them and putting him in smash as playable is not a good idea - except for Dark Matter who has been a final boss for 3 games, or more if you count pseudo-Dark Matters like Dark Nebula, Dark Mind and Magolor's final form as well -, but this is what looks to be the most likely character so far).
Someone from Rhythm Heaven is very possible as well... there are a lot of potential fighters in the trophies, there is Karate Joe, the Chorus Kids, Marshall and the wrestler.
Maybe King K Rool or Dixie? They both have a trophy.
The 3 Mii trophies are also missing in that screen I think.
Looks like someone is missing from the character select screen since the leak of the 3DS version, and now there is this DLC thing, so I think it's very possible that Mewtwo won't be alone.