The GameCube controller will be compatible for Super Smash Bros. Ultimate on the Switch.
Super Smash Bros. Ultimate director Masahiro Sakurai made the announcement on today's Nintendo E3 2018 Direct which focused heavily on the new Smash Bros. game.
Sakurai announced not only that every Smash hero in the history of the series will be playable, but also that Ridley will be joining the battle. Smash Bros. Ultimate will come out on December 7, 2018. For more on today's Smash Bros. announcement check out our Super Smash Bros. Switch guide page, and for the rest of today's E3 news check out our E3 2018 guide.