With clever use of both hands and feet as well as a long board of wood and strong glue, one could effectively play three characters at a time!
Well, from what I've seen, all special attacks besides the turnip have been shown. Think it could be the new Down-B?
It wasn't? I faintly recall seeing it in a video, which made me assume that the neutral b, which we only saw in a screenshot, was changed... you know, to give some hope to the Toad supporters.
But another theory that I find far more likely now, is that the victory poses at the end of the battle will now be displayed right on the stage. And maybe, when two characters who are somehow related to one another team up, they pose together. That would be another explanation for why Bowser is dancing as well.
But... the Gardevoir theory is just far-fetched, really. ^^;