Where is mr mime in pokemon firered?

Mr. Mime is not found in Pokemon FireRed. He was introduced in Generation I, but only in the Japanese version of Red and Blue.

When the games were localized for international release, Mr. Mime was removed due to concerns over his design and potential for misinterpretation.

You can, however, obtain Mr. Mime in Pokemon FireRed through trading with someone who has obtained him from another game.