The following are known Action Replay Codes for Dragon Warrior Monsters on Nintendo Game Boy / Color (GB / GBC). These codes were also known as GameShark Codes and in most cases will work on both devices.

Device Compatibility: Action Replay & GameShark

1st Slot Infinite HP (In Battle)
01ffa3db

1st Slot Infinite MP (In Battle)
01ffc3db

1st Slot Max Attack (In Battle)
01ffe3db

2nd Slot Infinite HP (In Battle)
01ffa5db

2nd Slot Infinite MP (In Battle)
01ffc5db

2nd Slot Max Attack (In Battle)
01ffe5db

3rd Slot Infinite HP (In Battle)
01ffa7db

3rd Slot Infinite MP (In Battle)
01ffc7db

3rd Slot Max Attack (In Battle)
01ffe7db

Infinite Money
01ff4bca
01ff4cca