From WiKirby
Kirby's Dream Land 2 artwork.
Bouncy is a pink, top-like enemy that debuted in Kirby's Dream Land 2, where it is referred to as Bouncy Ty. It behaves just as its name implies, by bouncing around. Its continuous bouncing movement, which is sometimes self-propelling or stationary, is a product of its springy underside. This commonplace foe, like the Bronto Burt and N-Z, does not reward Kirby with any Copy Ability if swallowed.
In Kirby's Return to Dream Land, a bigger version of this enemy known as SisterBound appears, which is usually found amidst its smaller cousins.