1. Mt. Silver (Post-Game)
* This is the most well-known encounter. After you defeat the Elite Four and become the champion, Steven will be waiting for you at the peak of Mt. Silver. This encounter serves as a very tough post-game challenge.
2. Lilycove Department Store (During the Main Story)
* This encounter is much earlier in the game. During your journey through the Hoenn region, you can find Steven on the 4th floor of the Lilycove Department Store. He will challenge you to a battle using a Metagross. This battle serves as a brief introduction to Steven and a preview of his strength.
Keep in mind that Steven's team changes depending on the location and time of the encounter. He is a very strong trainer, and his battles can be quite challenging, especially in the post-game scenario.