During gameplay, hold down the L and R trigger buttons and enter in these codes. When you enter in these cheats, you will hear "You cheated" confirming that you entered them in correctly.

click Right Analog-stick, A, click Left Analog-stick(2), quickly press Y, B
A, click Right Analog-stick(2), White, Y, X

On the level Lungfishopolis, there is a hidden picture at the very back of the level. At skyscraper island, where the biggest buildings are, go to the corner of the last tall building. Rotate the camera around till it is above you and to the right a bit. If done right, you'll find a picture of a programmer's girlfriend on the backside of the mountain.

Clairvoyance: Go open the fridge in Boid's mind.
Confusion: You can find it in Bullfighters home in Edgar's mind.
Invisibility: Go and see Ford after you have ranked up enough.
Levitation: Complete Milla's dance party
Marksmanship: Destroy the Mega Censor in Sasha's mind,
Pyrokinesis: See Ford after you have ranked up enough.
Shield: Release the lungfish from prison over in lungfishopolis.
Telekinesis: Go and see Ford once you have ranked up enough.