A message will confirm the correct code entry.

Unlimited ring charges for Frodo:
Quickly press Y, B, A, B, Y, X during game play while idle.

Unlimited magic for Gandalf:
Quickly press X, Y, A, X, B, X during game play while idle.

Unlimited ammunition:
Quickly press X, B, Y, A, X, B during game play while idle.

Unlimited health:
Quickly press Y, A, X, B, A, Y during game play while idle.