Amazon.com: Super Smash Bros. GameCube Adapter for Wii U : Nintendo Gamecube Controller Adapter: Video Games
Mayflash GameCube Controller Adapter for Wii & Wii U (Dual Pack), White - Walmart.com
Amazon.com: Mayflash Nintendo GameCube Controller Adapter for Wii/Wii U : Video Games
GBros. Adapter | 8BitDo
Turns Out The GameCube Controller Adapter Won't Be Compatible With Other Wii U Software | Nintendo Life
raphnet. - Classic controller to Gamecube/Wii adapter
Switch Gamecube Controller Adapter, Super Smash Bros Gamecube Adapter for Nintendo Switch, Wii U and PC USB with 4 Ports - Plug & Play, No Drivers Needed - Newegg.com