Defeat All 10 Bosses Its Simple Really the easiest way is to be hammer Kirby or rock Kirby
By beating 13 foes on the Arena
the hammer ability.
you don't Kirby Super star ultra beats you!
you have to beat at least 13 bosses in The Arena
by beatin the other modes in kirby super star
You unlock all of the bloopers after you beat the True Arena.
Kirby Super Star and Kirby Super Star Ultra
By beating all 19 foes of the Arena
Nightmare is the last boss in Kirby's Adventure for the NES and Kirby: Nighmare in Dreamland for the GBA. He does not, however, appear in Kirby Super Star Ultra.
In Kirby's Adventure,Kirby Super Star,Kirby Squeak Squad and in Kirby Super Star Ultra yes.
There is no Crystal ability, at least not in Super Star Ultra.
You have to beat the arena, then go back to the spot where the arena is, click on true arena and there you go.