That multi-controller options has always been pretty obvious.
One they say hang on to your Gamecube controllers which is a strong hint, plus the game is non-motion so... They would never make a game that is inplayable with the systems main controllers. Three classic controller is basically just another gamepad option like Gamecube, this is an easy way to attract people to buy them (who don't know about backwards compatibility).
But the Wii-mote only is kind of shocking... Is it even possible to map all the controllers with it? If it's possible I still don't see how this could be intuative at all.
I have 2 gamecube controllers and 2 wii controller sets... I can do it I'm hoping for a few other good games that support GC too, besides MK.