The following are known Action Replay Codes for Mega Man Battle Network 5: Team Colonel 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
a1722b2e
3f1b0039
96695b7f
873db9ae

Max Health
26105045
e087c1b8

Infinite Health In Battle
a069b6f6
6105ccbf

Max Custom Gauge
bddf27b7
2c0e45d1

Infinite Zenny
2d47e81b
639dc281
003a536d
2738cec5
4464b0b5
d6aeca25

No Random Battles
cc18e87c
a1ef6916

Infinite Puzzle Time
4975a7a7
1b161343
d90465a8
2ed8c3b4
cd4c0f28
0017b704
9f6b6aab
2efee35c
Note: Press Select when the puzzle is complete.