Most of the costume alterations are just color schemes anyhow. Couldn't be that difficult.
And if they do what I want them to, which is a "create a costume" option, then that would likewise be the coolness.
On a slightly more serious note, I don't see why there couldn't be a control scheme for the Nunchuk+Wiimote configuration.
Nunchuk - Joystick = motion, C button is shield, Z button is grab.
Wiimote - A = A attacks, B = B attacks, A+B = something else entirely (I bring this up since they're easier to push at the same time now), and Down on the d-pad could be your jump button if you don't like hitting up. The minus button is a select button, the plus button is start. 1 and 2 do... nothing?
Hmm... it'd be kind of cool if the motion sensing in the wiimote would perform smash attacks, but I doubt it. If you had several people playing together, SOMEBODY would get hurt.
And don't forget that a lot of stuff is being planned out for people who aren't tournament players. Melee is hugely popular disregarding its depth. 8 people on a moderately sized stage would be chaotic as hell, but for most people, chaos = fun.
And I won't lie, I would probably be a huge fan of 3v3 tournaments. The only downside is that with the wireless classics you would have lag, which a tournament player cannot tolerate.
My $0.02.