The following are known Action Replay Codes for Fantastic 4: Flame On 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
0b7fd036
3333923f
0b062db0
c814abe5

Infinite Health
49c47b50
9bb598ba

Invincibility
e8979dba
88740f8d

Infinite Cosmic Moves
3daccc64
21a902b8

Max Score
66d175b0
bb5f11e8

Always Have Low Time
94df7842
3ecf2952