Today, the official Japanese twitter account for Super Smash Bros. announced that four spirits from Cuphead will be available in Smash on February 14th (Friday). These spirits will be available for five days and include Cuphead, Mugman, the Devil, and King Dice.
At the time of this writing, no other information is available.
Author's Note: Are you excited for Cuphead spirits? I am. Glad to see such a good game getting recognized in Smash. Let us know in the comments below!