Wii U owners are getting GameCube controller support later this year, when the previously-announced adapter launches alongside Super Smash Bros. for Wii U this November.
Unfortunately however, it looks like support for the controller won't extend beyond Smash, as the Big N has clarified in a statement to GameSpot that the adapter will only work with Nintendo's upcoming brawler. "The GameCube Controller Adapter for Wii U is compatible with Wii U and Super Smash Bros. for Wii U specifically – it is not compatible with any other Wii U software."
The release date for Super Smash Bros. for Wii U was announced by Nintendo yesterday. It'll arrive on store shelves November 21. At that time you'll be able to purchase for yourself a GameCube controller adapter, and, if it's your sort of thing, a whole bunch of amiibo figurines.