Invincibility:
Pause game play, then hold R1 and press Triangle, Square(2), Circle(2), X(2), Triangle. A roar will confirm correct code entry.

Alternate colors:
Highlight George, Ralph, or Lizzy at the character selection screen. Press Up after selecting a character to choose a new color.

Hint Flying:
Press Jump, then while in the air rapidly press Jump to have your character to flap their arms. Your character will fly and slowly descend to the ground. This trick works best if you jump off a tall building.