Does Zach Tyler Eisen and Mitchel Musso play Aang?

That's a good question, but you're mixing up two different things. Here's the breakdown:

* Zach Tyler Eisen voiced the character of Aang in the animated series Avatar: The Last Airbender.

* Mitchel Musso played Zack Martin in the Disney Channel series Hannah Montana.

While both were child actors in popular shows, they are not the same person, and Mitchel Musso did not play Aang.