You fight 10 foes with only 5 tomatoes to fill up your life. 7 of the foes are from Revenge of the King. The last four foes are called the final four which consists of in order Masked Dedede from Revenge of the King, Wham Bam Jewel from Helper to Hero, Galacta Knight from Meta Knightmare Ultra, and Marx Soul from nothing.
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.
Defeat All 10 Bosses Its Simple Really the easiest way is to be hammer Kirby or rock Kirby
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.