Secret Characters
There are more versions of Kirby when you beat the game. Here they are and how you can get them.
Waddle Dee Ball-Finish the game once. When you start a game from the save file, Waddle Dee will be revealed as a new playable character. He only has 4 hit points and can't obtain powers. Also,he's lighter than Kirby.
Dedede Ball-Unlock the Waddle Dee ball. You can then get the Dedede ball for 20 medals at the Medal Swap. He has 7 hit points and can't obtain powers. Also,he's larger and heavier than Kirby.
Waddle Doo Ball-Beat the game once,then insert Kirby the Amazing Mirror or Kirby: Nightmare in Dreamland in to the GBA Socket in your DS. When you start a game of Kirby: Canvas Curse,Waddle Doo ball will be avalible. Or you can beat the game with all 4 characters. Waddle Doo has 5 hit points and the Beam ability. He can't obtain any powers.
Meta Knight ball-Unlock the Dedede ball and buy it for 20 medals. The Meta Knight ball will be avalible for 25 medals. This knight has 3 hit points,and lighter and stronger than Kirby.