In Amazing Island, the Black Evil has taken over the island, and the Maboo Tribe has called upon you to bring order and outcast the evil that has taken control. To do so, you must create your own creature and train it up, entering it into various competitions against the Black Evil and working towards the main goal. As the competitions are completed, you will unlock new features to improve your own creature in speed, strength, and general appearance.

While the gameplay relies on your active gamepad skills (mostly pressing a button as fast as possible with minor variations), the chances of success are dictated by the monster's statistics. So, for example, a dragon would be beneficial for a flying mini-game. Those statistics can be further enhanced with items bought at shops.

Play single and multiplayer battles on the GameCube, or upload your creatures to the Game Boy Advance, taking them on the road to challenge your friends and unlock items and features for the creatures you design.