Asked in Pokemon Diamond Pearl and Platinum
5th gym leader Pokemon Diamond?
Fantina. She is located in Hearthome City. She specializes in Ghost-types. You first have to find her by the Hearthome City Contest hall. Her Gym has various levels. Fantina's room is located on the fifth level. The Pokemon she uses are Drifblim, Mismagius and Gengar. After you defeat Fantina she sometimes appears in Master Rank Super Contests, competing with her Drifblim