Prince Fluff is a character who appeared in the Wii game, Kirby's Epic Yarn, where he was the second players character. He lives in the wool sock Patch Land that Kirby gets transported into and he appears
to be part of Kirby's species. Unlike Kirby, however, he doesn't have blushes on his cheeks. He frowns during gameplay. For some odd reason, Prince Fluff doesn't need a power-up to transform, unlike Kirby. A little is known, despite the game being released already.
Data was found for Prince Fluff as playable in Super Smash Bros. Zero, with a file called PRI_FLU but he was demoted to a assist trophy where he Yarn Whip's, building up Damage, and then strikes the opponent with the Tank-Bot which could deal a KO if the damage on the player is high. The Tankbot was probably to be his Final Smash. His assist status was later revived for Super Smash Bros. Uproar.
A screenshot of Epic Yarn with Prince Fluff assisting Kirby.