Last week Nintendo distributed an update for its Switch console that brings the firmware up to v. 4.0, and while the notes accompanying the update made no mention of it, it appears the console can now support GameCube controllers.
It's a neat little feature, albeit one that requires Switch owners to use a USB adapter to wire up the GameCube gamepad to the Switch. Once connected, it works like a wired Switch gamepad, sans modern conveniences like a "Home" button.
Nintendo released just such an adapter (pictured) for the Wii U a few years ago, alongside the Wii U entry in its venerable fighting game series Super Smash Bros.
Multiple entries in the series are still played competitively today by professional players, many of whom play using GameCube gamepads.