At the Main menu press - and + at the same time to display the code entry screen then enter one of the codes listed below and move up or down to choose numbers from 0-9. If the code has been entered correctly you will hear a monster sound confirm as confirmation. The codes aren't permanent, When you turn off your Wii they will be disabled.
Invincible to Military Attacks - 986960
Demo Mode With Two Random Monsters - 082864
Instant Demo Mode With Two Random Monsters - 874098