The following are known Action Replay Codes for Mega Man Battle Network 4: Blue Moon on Nintendo Game Boy Advance (GBA).

These are Action Replay Version 3 (V3) Codes.

The codes should work with the region specified but may work for other regions as well.

(M)
a7e4a2ca
7d29f307
574fbd83
b5f10216

Infinite Health
a8e6982b
e6cc4aa0

Full Custom Gauge
9c5057e6
49ff8345

Chips Do 9000 Damage
f1c68bd4
fecac79d
119b1541
da4a7313

Select Deletes All
6d473537
693e0d4d
0738ece9
743be779