Finding a verified "unlock all cards" mod for Yu-Gi-Oh! Duel Generation is challenging because Konami officially shut down the game's servers

Customise your profile with any character from the anime series. How to Install the Mod Safely

No verified all-cards mod exists for Yu-Gi-Oh! Duel Generation that I can recommend. Avoid downloading such files from forums or YouTube links — they are almost always scams or malware.