Yu-Gi-Oh! GX: Duel Academy Cheats

After achieving the rank of King of Games, a new room called Principal's Office will become available at the Duel Academy location. You'll now be able to duel with Chancellor Sheppard. Beware, as losing your first duel with him will knock your rank down to Prince of Games.

Subsequent duels with Sheppard will allow you to change your character's name after beating him.