What I would like to see is a set of characters that are deliberately better than all of the others, and can be used for epic fights (banned in tournaments, though). Giga Bowser, Master Hand, Ridley, Taboo... matching three normal characters against Ridley to take him down would be incredible, plus people would have no reason to whine that Ridley isn't playable and they'd have no reason to whine that he's downsized/underpowered.
Here'd be my list of 'uber' characters:
Master Hand
Crazy Hand (slight clone to Master Hand)
Giga Bowser (clone of Bowser)
Ridley
Taboo (if he's in the next Smash)
Ganon
Mewtwo (make him far more powerful than in Melee and he could pwn)
Andross (meh I'm running out of ideas)
Dr. Robotnik
Possibly more; may seem like a stupid idea, but it would make for some very interesting bouts...