Were do you find hethrome city gym leader in Pokemon Diamond?

The Gym Leader of Hearthome City in Pokémon Diamond is Fantina, a Ghost-type specialist. To find her, you must first make your way through Hearthome City Gym, which is located on the western side of the city. The Gym is a large, haunted house with a maze-like interior. You will need to use your Pokémon's abilities to solve puzzles and defeat trainers in order to progress through the Gym. Once you reach the end, you will face Fantina in a Pokémon battle.