The following are known Action Replay Codes for Star X 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
29d939f1
3f054541
996ea039
38ed88bd

Infinite Health
c3ea92ed
7c6ece11

Infinite Lives
709e28ed
69b4d407

Infinite Bombs
b41e6278
ae9b3950

Max Weapon Power
e90fe345
34fc38bc

Weapon X
2166b07c
45c827bb

Quick Score Gain
043e4932
8a9ac89c

Start on Level 2
640eae49
3dc7c02b

Start on Level 3
96dac428
dd7c7b07

Start on Level 4
8c590083
a684c9b2

Start on Level 5
6c05c134
47a54147

Start on Level 6
1f720e22
f7c06d31

Start on Level 7
a0d97bb7
2f84f63e

Start on Level 8
7b685cb4
60a1cd45

Start on Level 9
e463d05c
af166d23

Start on Level 10
66b14b60
caa0e738

Start on Level 11
eaa036aa
423afc55

Start on Level 12
e161b762
0bde1d65

Start on Level 13
f85c6ebc
41e3d8a3

Start on Level 14
3464cca6
50993037

Start on Level 15
4dc54c0e
10a5b0a2

Start on Level 16
550506d1
61e592bb

Start on Level 17
5b067f12
8575ce84

Start on Level 18
5bc03858
262eb94a

Start on Level 19
ae105820
024a2f9d

Start on Level 20
8d13fa30
6317167f

Start on Level 21
f4428a74
cba5a6d7

Start on Final Level
bef7a50b
f34e3b90