Couple of things I noticed

[Micah]

You can see a couple of new stages in the vid. A Metroid, Ice Climber, and possibly the arena taking over for final destination. Also, Fox uses a smash ball when Zero Suit Samus is fighting. Does Zamus have a final smash?

 

[TwilightKing]

Hmmm.... If it's true that its one Smash ball per match, then that would be pretty odd that Zamus was there too :wacko:

 

[Trent the Paladin]

I'm sure you can play as either one, or they made it to where each player can only use 1 smash ball per match.

 

[Tyler]

I believe the smash ball only appears once during a match.