Sakurai, you magnificent bastard!
This is just splendid. Sonic & Mario co-op is like the dream of everyone who's ever owned both a Genesis and a SNES.
Plus, I hope Live & Learn is the music they're actually using for his stage. At least, I mean, one of the songs... some Green Hill Zone would be nice, too... to be honest, I think Shadow's theme would go in equally well. Maybe even an instrumental version of Chaotix from Heroes...
He looks to be (as expected) the speediest one there, but maybe a little tough to control...
Oh, and incidentally - in the trailer, after Bowser and Peach's inexplicable dancing, Pit appears to be descending from the sky!... does this mean a return of character intros (as with the original Smash Bros.?)
And finally, Ike's taunt (if that's what it is) looks cool.