Some new Star Fox Characters may be added in SSB4. It was hinted in Falco's smash taunt:
Fox: Well, it is a Brawl, after all. Everybody's in on the fight!
Peppy: That gives me itching for some action. I want in!
Slippy: No way! Old-Timers like you ride the bench. The fight's mine!
Krystal: What are you two thinking? I'm the only one who can come through in a fight like this!