I just recently homebrewed my Wii U for Nintendont and wanted to see if it was possible to get this controller to work. I've done some research but can't find anything. :
Super Smash Bros Wii U Edition Nintendo Gamecube Controller W/ Box DOL-003 | eBay
Mario Kart Wii CTGP - Using Gamecube controllers on Wii U for MKWii - YouTube
Is it possible to mod your Wii U to connect to the wireless switch GameCube controller? : r/WiiUHacks
Amazon.com: Super Smash Bros. Edition GameCube Controller : Video Games
How can I play a wii game with a GameCube controller if I have the game in the Wii U menu? : r/WiiUHacks
Officially Licensed GameCube Controller Wannabes for Wii U and Nintendo Switch - YouTube
New 2020] How to use Official GC adapter on GC "Emulator" for WiiU! (nintendon't) - YouTube
Wii U Gamecube Controller Adapter - Brook Gaming
Amazon.com: Y Team Controller Adapter for Gamecube, Compatible with Nintendo Switch, Super Smash Bros Switch Gamecube Adapter for WII U/PC with 4 Port : Video Games