Switch's 4.0.0 update now allows for GameCube controller support with Wii U GameCube Adapter
Super Smash Bros. Ultimate: Does the Wii U GameCube Controller Adapter Work on Switch?
Amazon.com: Mayflash GameCube Controller Adapter for Wii U, PC USB and Switch, 4 Port : Video Games
WII U Gamecube控制器連接器【適用於WII U、NINTENDO SWITCH 和PC USB】 – DimBuyShop
Controller Adapter 4 Port for Gamecube Controller to WiiU & Switch & PC : Amazon.com.au: Video Games
Official Nintendo GameCube Controller Adapter Switch Wii Wiiu - Brand New | eBay
GameCube Controller Adapter - Nintendo Switch - retrospiel - new game, 29,99 €
GameCube Controller Adapter For Wii PC and Nintendo Switch
TTX Tech GameCube Controller Adapter for Wii U and Switch - Micro Center
Lexuma GameCube 控制器連接器- 適用於Wii U, Nintendo Switch和PC USB – Lexuma Distribution
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
GameCube Controller Adapter for Wii U + Nintendo Switch [Nintendo Accessory] | Walmart Canada
Lexuma GameCube 控制器連接器- 適用於Wii U, Nintendo Switch和PC USB – Lexuma Distribution
915 Generation For Gamecube Controller Adapter For Nintendo Switch Wii U @ Best Price Online | Jumia Egypt
4-Port Controller Adapter for GameCube® Compatible with Nintendo Switch® / Wii U® / PC/ Mac®
4-Port GameCube Controller Adapter for Switch Wii U PC Mac
Nintendo Wii U & Switch GameCube Controller Adapter - OFFICIAL OEM | eBay
WHOA! GameCube Adapter Works on Nintendo Switch! - We Show it Off! - YouTube
JYS GameCube Controller Adapter GC NGC Adapter for Nintendo Switch, Wii U and PC - Tech Smart Philippines
GameCube Controller Adapter for Nintendo Switch 4 port to USB Wii U PC 3 in 1 - Walmart.com
Just found out the Wii-U adapter works on switch! It's time to get serious about smash. : r/gaming