The following are known Action Replay Codes for Madden NFL 2000 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

Always First Down
0101f1da

Always Fourth Down
0104f1da

Home Team Score 0
0100c6c2

Away Team Score 0
0100c7c2

Home Team Score 50
0132c6c2

Away Team Score 50
0132c7c2