What episode of Pokemon did dawn return and in which region?

Dawn doesn't actually return to the anime in the way that you're likely thinking. She makes brief appearances in some episodes, but she doesn't return for a significant arc or storyline.

However, she does make an appearance in the Kalos region in Episode 835: "An Old Friend, A New Adventure!" where she briefly joins Ash and his friends for a Pokémon Showcase.

It's important to note that this is a very short appearance, and she doesn't stay for the whole episode.

Do you have any other questions about Dawn, Ash, or the Pokemon anime?