Little Mac seems to wreck people with his ground game, but is a somewhat weak fighter in the air and has a mediocre recovery, as evidenced by the Wii Fit Trainer getting the better of him. He's probably going to be in the mold of a character that has a strong early game, but falls of late, in the mold of the anti-Lucario, who gets stronger when he takes damage. If you can get a good lead early as Little Mac, you're going to dominate.
Also, that K.O. move looks REALLY OP. Anyone else thinking this?