The following are known Action Replay Codes for Mat Hoffman’s Pro BMX on Nintendo Game Boy / Color (GB / GBC). These codes were also known as GameShark Codes and in most cases will work on both devices.

Device Compatibility: Action Replay & GameShark

Stop Timer
9109bdcc

Max Super Meter
9138dfcc

Have All Covers
911e62ca

Have All Medals
910663ca

Enable Jump (Star Level)
910980cc

One Letter Needed To Win
91056ccb
91056dcb

One Star Needed To Win
91096dcb

Max Score
910984cc
910985cc
910986cc
910987cc
910988cc
910989cc