The following are known Action Replay Codes for Magical Tetris Challenge 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

Quick Win for Updown Tetris
011225ce

Max Lines
019925cc
019926cc

Max Score
01997bc6
01997cc6
01997dc6

All Coins
0166ffc6