Unlike Kirby and Megaman, Emerl copies EVERYTHING.
For example:
Mario's Smash fwd
Fox's tilt up
C.Falcon's jab 1
Link's jab 2
Falco's jab 3
Kirby's grab up
... you get the idea...
Emerl would be an AWESOME addition. But he would:
a.- be banned from competitive play
b.- getting all skills for him would bring too much attention on him, turning SSBB into Sonic Battle 2.
c.- everyone and their mothers would use Emerl, since he'd have any move and could be improved beyond every other character.
I am hoping for Sonic Battle 2 though.. With G-Mel instead of Emerl.