The following are known Action Replay Codes for Catz 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

Full Bar Happiness Sophisto
80aad180

Max Energy Sophisto
80aa9aa1

Max Affection Sophisto
80aad6a1

Max Happiness Jester
80aa51a1

Max Energy Jester
80aa95a0

Max Affection Jester
80aad6a0

Max Happiness Homeboyd
80aad1a1

Max Energy Homeboyd
80aa1aa1

Max Affection Homeboyd
80aa56a1