To unlock all missions and planes:
Go to the main menu, hold the L trigger and R trigger and enter X, LB, RB, Y, Y, RB, LB, X.
To unlock God Mode:
Pause the game and hold the L trigger and enter X, Y, Y, X. Now hold the R trigger and enter Y, X, X, Y.
To unlock Increased Attack Power:
Pause the game and hold the L trigger and then enter LB, LB, RB. Then hold the R trigger and then enter RB, RB, LB.