The following are known Action Replay Codes for NBA Hoopz 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 Code Timer
910916cd

P2 Scores 100
916430ce

P2 Scores 0
910030ce

P1 Scores 100
91642fce

P1 Scores 0
91002fce

Start On Fourth Quarter
910394ce