Reach level 25 with each of the four original characters to unlock Falconess, Minotaur, Tigress, and Jackal. Load your level 25 character and start a new one through character management. Hold Turbo and you will notice your character has turned into its counterpart. For example, Barbarian becomes Minotaur and Wizard becomes Jackal. They can be selected with any color.
Note: A controller with an auto-fire feature is useful for this trick. Begin a game in the first level in the mountain world. Go to the first set of stairs. Stand in front of the stairs and keep holding Fire. Unlimited green trolls will keep coming at you. Leave the game in this position for as long as needed to maximize your levels.
Full pause screen
Pause the game and press X + Y.
Allow the game to idle for a short time and a screensaver will appear.