Monster Force

In-game reset:
Press Start to pause game play, then hold L + R + A.

Invincibility:
Press Start to pause game play, then hold L + R + B and press Down. A sound will confirm correct code entry. Note: Enter this code again to disable its effect.

Play as Drew or Mina:
Hold L + R + B + Right at the character selection screen.
Information in this section was contributed by jenniebgood.

Alternately, to play as Drew complete the game with a "Crystal" rank on all levels. To play as Mina, successfully complete the game.

Complete level quickly:
Hold Right + R + L + A du ring game play. Alternately, hold Up + R + L + A.
Information in this section was contributed by Beauhere.

Hint: Multi-player arenas:
Complete the indicated task in single player mode to unlock the corresponding arena in multi-player mode.

Atlantis arena: Defeat the Atlantis Shadow Creature.
Castle arena: Complete the game.
Cemetery arena: Defeat the Cemetery Shadow Creature.
Clouds arena: Defeat the Clouds Shadow Creature.
Desert arena: Defeat the Desert Shadow Creature.
Factory arena: Defeat the Factory Shadow Creature.
Garden arena: Defeat the Garden Pumpkin Boss.
Temple arena: Defeat the Temple Dragon Boss.
Village arena: Defeat the Village Shadow Creature.