Where is Dana in Pokemon crystal the one who gives you a thunder stone?

Dana, the person who gives you the Thunder Stone in Pokémon Crystal, is located in Goldenrod City.

Specifically, she's inside the Goldenrod Department Store on the second floor in the northwest corner. You'll find her standing near some shelves, and she'll give you the Thunder Stone if you talk to her.

She's a bit of a tough one to find, but she's a great source for evolving your Pikachu!