The following are known Action Replay Codes for The Land Before Time 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

Infinite Health
9109a0c0

Max Flowers
9163a2c0

Max Bags
9163a3c0

Always Cera
9100e5c8

Always Little Foot
9101e5c8

Always Ducky
9103e5c8

Always Spike
9104e5c8