Battle Garegga Cheat Codes for Arcade

Harder Mode
At the Title Screen, press B, Start.

Special Mode (Hard + Second Round)
At the Title Screen, press A, B, C, Start.
Bonus Plans
At the Title screen, press Up, Up, Down, Down, Left, Right, Left, Right A, B, C, Start.

Extended Mode (Second Round)
At the Title Screen, press A, Start