GameCube Controller for Nintendo Wii and GameCube [2 Packs]
CORN Classic 2.4G Wireless Controller Gamepad Receiver Adapter Compatible Nintendo Wii U Gamecube NGC GC Console (Black) - Newegg.com
Wii U's GameCube controller will support more than just Smash Bros. [updated] | VentureBeat
Wii U Gamecube Adapter Compatibility Test - YouTube
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