The following are known GameShark Codes for Batman Beyond: Return of the Joker on Sony Playstation (PS1).
These codes were also known as Action Replay Codes and in most cases will work on both devices.

These codes are for the U.S. version of the game.

• Infinite Health
  8001A276 2400
• Infinite Lives
  8001D4EC 2400
• Infinite Dark Knight Discus
  80028C22 2400
• Stop Timer
  8006CF1C 0000