Where is the dance theater in Pokemon soul silver?

There is no "Dance Theater" in Pokemon SoulSilver. It's possible you are thinking of the "Move Tutor", which is located in the Goldenrod City area. Here's how to find it:

* Go to Goldenrod City: Head north from Ecruteak City.

* Find the building with the dancing figures: The Move Tutor is located in a tall building near the Pokémon Center, with dancing figures visible outside.

The Move Tutor doesn't have anything to do with dancing, but it allows you to teach your Pokémon new moves for a fee.