From a joke character stand point, I think Peppy would have gotten in over Slippy. He could've been like the playable Mr. Resetti and told everyone about "Barrel Rolls".
Edit:
There's some info on Wolf out.
B - Blaster. Less range fires slower than fox and falco, but looks stronger.
Forward B - Same as Fox and Falco's shadow fox dash thing. Only Wolf's goes slightly upwards too. At about a 25 degree angle.
Down B - Reflector
Up B - Like Firefox, only it doesn't really charge, goes really high though. Maybe it only goes up?
Final Smash - Landmaster (derp)