Enter the following commands on the password screen:

Big Boots:
Right Trigger, White, Y, A, Left Trigger, B, White, X.

Big Hands:
Right Trigger, White, X, Left Trigger, White, Right Trigger, Right Trigger, Y.

Big Heads:
Left Trigger, Black, B, White, White, B, Black, Left Trigger.

God Mode:
Y, A, B, X, B, A, A, Left Trigger.

Infinite Ammo:
A, Left Trigger, Left Trigger, Black, B, White, Left Trigger, Left Trigger.

Instant Health:
X, Right Trigger, A, Y, Black, B, A, Right Trigger.

Invincibility:
X, X, X, Right Trigger, A, Left Trigger, Left Trigger, Y.

Refill Ammo:
Black, B, A, Right Trigger, Right Trigger, A, Left Trigger, Black.

Topsy Turvy Bomb:
Y, A, B, B, A, B, White, White.

Unlock all levels:
Y, White, Black, Left Trigger, A, Right Trigger, Right Trigger, Y.

Unlock all movies:
A, Y, A, Y, Black, Right Trigger, A, Y.