8BitDo has just announced a wireless adapter for the Nintendo Switch. This allows you to plug in both GameCube and Wii Classic controllers into the adapter, which is then wirelessly connected to the Switch. The main page lists the adapter as “lag-free”, but that’s hard to believe considering you first have to convert the controllers signal to bluetooth, which itself have the potential for lag.
The adapter will ship December 7th for $20. More information on the adapters can be found here and pre-order links are below: http://www.8bitdo.com/gbros/