Argus Steel is the leader and boss of the thieves, He along with his daughter Millis Steel, Marilyn Flame and Ninja Riot are hunting Diancie to capture her and awaken Diancie's power to create diamonds before stealing the Pokemon and fortune for himself. During Yveltal's rampage his Honedge, Doublade were turned into stone by Yveltal's attack "Oblivion Wing" He, his daughter and his Aegislash use their airship to take down Yveltal with missiles but Yveltal avoid them and flies over and hit the center of the airship fired his Oblivion Wing turning Argus, Millis and Aegislash into stone and crash into the lake. Later he, his daughter and his Honedge, Doublade and Aegislash were revive by Xerneas after Yveltal's rampage is over. In the credits of the film He and Millis Steel opens their own chocolate shop together.
- He will become Emerl and his friends' enemy in Team Robot in Pokemon: Diancie & The Cocoon of Destruction.