I'm hoping Diantha's theme to make an appearance in SSB, now that the Kalos Pokemon League is now a stage, so I can ruin its elegent feel by the random shouts and grunts from various Nintendo characters. Outside of that, I also hope for Purple Coins theme, Punch Bowl, Koloktos theme, and C.R.O.W.N.E.D. to be included in the My Music soundtrack.
omg substitute greninja
Speaking of Greninja, surprise appearances. I could remember people speculating on a Mewtwo return, or Darkrai/Zoroark as new Pokemon in SSB. Greninja's moveset looks pretty cool, are those water kunai or something? Couldn't get so much of a good look D:
I like how Sub's used though, looking forward to it.
Both Darkrai and Zoroark are confirmed to be not playable from Greninja's trailer; they will be Pokeball Pokemon. As for Mewtwo, he now has to compete with Jigglypuff to take the 5th slot for Pokemon, but I'm leaning towards Jigglypuff for two reasons: 1) She's a member of the original 12, and 2) Greninja's part Dark, so Mewtwo's Psychic abilities will do jack on him, seeing as how Sakurai implanted type advantage on the Pokemon characters in Brawl (Ivysaur doing more damage to Squirtle with Grass moves, Rayquaza taking less damage from Charizard's Rock Smash, etc.).
We may have lost Ridley, but there is still another reptilian villain we can hope to return, because the Kremlings are going to be in Smash Run, meaning Nintendo still hasn't forgotten about them despite taking the benchwarmer for one-time villains in Retro Studios' games.
Since the 3DS is going to be released earlier than expected, and by the time the leaks from early releases are up, we'll soon find out about the whole roster, since both versions will include the same characters.