To unlock the jump game next to the options button on the main screen, beat the game with all five characters. Select the game file and a message will pop up. You can now play the Jump Game without beating a level.
To unlock the first new character, Waddle Dee, beat the game once. He is exactly the same as Kirby except for the fact that he has four life, is a bit lighter, and cannot obtain powers.
The second new character, King Dee Dee Dee, is purchasable for 20 medals once you get Waddle Dee. He is large, strong, heavy, sinks in water, wind has less of an affect on him, has 7 life, and swings his hammer when you touch him. If you hold the stylus on him, he will continue to swing his hammer. He cannot get powers either.
The third new character is Metaknight. He is purchasable for 25 medals once you get King Dee Dee. He is almost twice as fast as Kirby and cannot get powers, but he only has 3 life.
The fourth character, Waddle Doo, (the kind with Beam ability), is available only once you beat the entire game with all four of the other characters. He has 5 health, is Kirby’s weight, and has a perpetual Beam ability, touch him to use it. If you hold your stylus on him, the beam will continuously spin around him.
The game will keep track of what stages you beat with each character, and you will be awarded medals for beating the game with each character.