From my post over at CAG:
Let's see. This is speculation.
Wiimote sideways: Map attacks to 1/2 (as A/B respectively). Map shield to B trigger. You lose potential L cancels (though you can do this with the trigger), Z deflection (since no longer have that button), and short hops would be much harder to pull off (I'm thinking you'll have to rely entirely on quick presses on the D pad). I like using buttons for jumps, so this mode is out, unless motion control is used in a very novel and precise way. Smashes = juking left/right with the mote, for example. Could work, but I dunno. Precision kills in fighting games.
Wiimote + Nunchuk: D pad on the 'mote becomes the buttons. So down = B attacks, right = A attacks. Up/Left = used for jumping. B trigger = shield. Nunchuk has two buttons that can replace L and Z. So theoretically you have replicated full button placement from the GC controller. Again, this leaves out motion control, but if they implement it well, could be very useful. This is marginally better than the above.
Edit: Oh yea. You lose the C stick with both of the above. But if you are using it, you are a bitch and I hate you (when you use it).
Classic: Basically mimics the GC controller exactly, with only exception than the Z trigger might be lost, which is no big deal since you ought to be to live without it. Would be really funny if the 'mote was still usable. Wangmotation indeed.
GC/Wavebird: Probably will be the preferred method still. Depends if there are any new moves that take advantage of the above controllers.
Which brings up an excellent point: What if each setup gains its own advantages over the others? I.e., Wavebird is "standard." Motion enabled controllers get special moves, like maybe your Final Smash becomes based on motion and can inflict more damage. A pipe dream, but would be a reason people might use different control sets. That would add a lot of strategy, actually. That would put down the arguments about "well you used X setup and I used Y and you had the advantage."
Great. Now I'm going to be disappointed if that isn't in the game.
Hmmm. What was last Friday's update? I wonder if every Friday might be a "big" update.
Ahhh. I knew investing in a complete set of Wavebirds for the Wii was a good idea, as well as four extension cords. I guess I ought to snag a few more wired controllers just for good measure, even though I think I have enough already.