Big head mode:
Pause game play, then hold Select and press L1, Up, Right, L2, Up. Release Select. Then, hold Select again and press then press L1, Up, Right, L2, Up.

All Dream Keys:
Pause game play at the house hub, then hold Select and press Circle, L1, L2, L1, L2.

All Winks:
Pause game play at the house hub, then hold Select and press Left, Down, Right(3).

Full cogs:
Pause game play, then hold Select and press Down, R2, L1, Up, R2.

All 10 Moons:
Pause game play, then hold Select and press Up, L2, Left, R2, Left.

Restore Zzzs:
Pause game play, then hold Select and press Right, L1, Up, R1, L1.

Restore lives:
Pause game play, then hold Select and press L1, Up, Right, L2, Up.