Do you still have one of these bad boys? 
If you’ve managed to hang on to it over the years, good news: the new GameCube Adapter for Wii U has been confirmed by Nintendo Australia to support them! –
As if there was any doubt, eh?
Anyway,
A tidbit from Nintendo UK’s online store used to show a product description that mentioned the Adapter is “Compatible with all games supported by the Wii Classic Controller, Wii Classic Controller Pro and Wii U Pro Controller.” This would mean games like Mario Kart 8, Pikmin 3, Super Mario 3D World, etc, could support it too. We’ve recently learned, however, from Nintendo UK that “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 adapter was announced in the wake of the new Smash Bros game coming to Wii U, where everyone certainly vocalized their love for using the GameCube controllers when playing Smash. It will cost $19.99 in North America and £17.99 in the UK.
And be looking for Smash Bros for Wii U on November 21st in the U.S. and December 5th in the UK.
Thanks for reading!
-Kendo