To use a GameCube controller with the Nintendo Switch, players are required to have the Wii U GameCube Controller adapter and a GameCube controller. 

For some players, syncing the GameCube controller to the Switch is a very simple process: plug everything into the correct places, go to the Switch’s controller settings, go to “Change Grip/Order,” and hold down L + R. 

According to GameXplain, the finding was first reported on October 23 by Twitter user @MasterMewking:

 

On June 21, a video released by Spawn Wave Media showed the limited use of a GameCube controller on the Switch. At the time, only one controller was useable and Nintendo’s adapter did not work. However, with this new update, players are able to make use of the adapter and multiple GameCube controllers at one time. 

Although, as explained in GameXplain’s video below, there are some drawbacks with using a GameCube controller with the Nintendo Switch, namely not having access to the ZL and ZR buttons.