You can theoretically make your Digimon live forever by feeding them DigiSeabass and Chain Melons faster than they age.
Several cheats and codes have been discovered for Digimon World: Re-Digitize, which can be used to manipulate various aspects of the game. These cheats can be categorized into two main types: Action Replay codes and in-game cheats. digimon world re digitize cheats
Jijimon's PC Passwords Enter these codes on JiJimon's PC to unlock items or Colosseum battles. You can theoretically make your Digimon live forever
For the Decode version on 3DS, players can use the Re-Decode plugin to freeze aging, hunger, and poop status, or instantly digivolve via hotkeys. Password/code list - Digimon World Re:Digitize - GameFAQs and poop status