Cappy are regular enemies in the Kirby series and have very important roles in the anime, Kirby: Right Back at Ya!, as well.
In Games
Kirbys Dreamland
Cappy without his mushroom cap in Kirby's Dream Land.
Cappy made its first appearance. If Kirby tries to inhale it, he will always suck in Cappy's mushroom cap first before being able to inhale Cappy itself.
Kirbys adventure
Cappy has the same behavror like he does in kirbys dreamland.
Kirby Super Star
cappy is a reguar enemy and attacks by throwing his hat up the air.
Kirby Nightmare in dreamland
Same as kirbys adventure behavor.
Other Games
Cappy Appears in kirbys Block ball as a boss.
In the anime
Cappy appears as one of the most important roles in the whole anime as members of the cappy town.