Well I really don't know, but I'm going to get the game as well. I don't really want to use the nunchuck or the wii remote, but if you wanted to play 4 player with the wii remote and nunchuck, my guess is that you will need:
4 nunchucks, 4 wii remotes, and 4 matts. Expensive, I know. But if you have DDR: Mario Mix, then you can use that matt. That's what I have.