Instructions
Play the game until you face Psyphon in battle at the end of the second level on Earth. After you defeat the billboard that he brings to life, Ben loses the ability to change into Upchuck.
Pick "Vulpin" from the level select screen and then complete the ship mini-game to reach the planet. Use the D-pad to move the ship and avoid enemy projectiles while pressing the "B" button to return fire.
Complete the Vulpin level using Goop and Swampfire, the two alien transformations that you unlock. Use Goop to avoid damage from the acid rain puddles on the level and Swampfire to move through flames unscathed.
Select "Terradino" from the level select screen and complete the spaceship mini-game to unlock the Spidermonkey and Humungousaur transformations. Use Humungousaur to smash the columns on the level and Spidermonkey to swing through the level.
Complete Terradino and then select "Encephalonus IV" from the level select screen. Complete the spaceship mini-game to access the level and unlock the Brainstorm and Big Chill transformations. Use Brainstorm to charge the circuits on the level and Big Chill to glide towards out of reach platforms.
Complete Encephalonus IV and then select "MorOtesi" from the level select screen. Complete the spaceship mini-game to access the level and unlock Chromastone and Echo Echo. Chromastone is immune to the radiation on the level and Echo Echo can smash the crystals that block the way.
Complete MorOtesi and select "Null Void" from the level select screen. Complete the spaceship mini-game to access the level and unlock Jet Ray and Upchuck.