Can you get four moonstones on pokemon fire red?

Answer 1

Yes. I think there are actually five. Two are in Mt. Moon, One is in the Rocket Hideout below the Game corner in Celadon City,The guy who owns the game corner on Two Island will give you one after saving his daughter, and, If I'm not wrong, I think there is a hidden one on the ground floor of the Cinnabar Mansion. Otherwise, they are held by some wild Clefairy. Rarely. Hope it helped!