UPDATE: turns out Nintendo UK had made a mistake. So gamecube controllers only work for smash. Nintendo UK with false controller info and Nintendo of France with their november release for smash instead of europe's december 5th. Get back in the game NoE!
Good morning Tay.
The Nintendo UK site had a nice little bit that just made my morning:
This adapter will allow you to connect your GameCube controller to the Nintendo Wii or Wii U. Connect your GameCube controller to your Wii or Wii U console. Compatible with all games supported by the Wii Classic Controller, Wii Classic Controller Pro and Wii U Pro Controller.
Which means that any game for classic controller pro works with Gamecube controllers. So let me rephrase this:
HOT DOGS!: The Wii U now supports the greatest controller in history, have fun playing EVERYTTHING with improved controls, from Smash Bros to Mario Kart 8 to Hyyrule Warriors to Ninja Gaiden. Heck even Assassin's Creed the old en no DLC versions ;-)