This tutorial is based on sections of tutorials listed below.
https://sites.google.com/site/completesg/backup-launchers/gamecube/cmios
https://gbatemp.net/threads/gameboy-advance-original-sp-micro-as-gamecube-controller-for-wii.435282/
https://sdremix.com/installation/gamecube-installation/running-gcn-homebrew/
This requires a Wii U + Gamecube Adapter, and a Wii with Gamecube Ports or a Gamecube capable of running Homebrew!
You'll need to follow...
https://sites.google.com/site/completesg/backup-launchers/gamecube/cmios
https://gbatemp.net/threads/gameboy-advance-original-sp-micro-as-gamecube-controller-for-wii.435282/
https://sdremix.com/installation/gamecube-installation/running-gcn-homebrew/
This requires a Wii U + Gamecube Adapter, and a Wii with Gamecube Ports or a Gamecube capable of running Homebrew!
You'll need to follow...
[Tutorial] How to use a GBA as a controller for Wii U!