The following are known Action Replay Codes for Yu-Gi-Oh! World Championship Tournament 2006: Ultimate Masters on Nintendo Game Boy Advance (GBA).
These codes were also known as GameShark Codes and in most cases will work on both devices.

These codes are for the U.S. version of the game.

Master Code – Must Be On
74050976
aaa70689
4dd0446c
4e3c0d2f

Maximum / Infinite DP
e293ab84
394204f1

Instant Win
80c06834
cde02473