Good idea for a moveset xD. I think a Pokemon that would probably rival Gengar would be the powerful Chandelure. It has a unique typing and has a whopping Special Attack of 145. It has really useful abilities and is a bit more bulky. I mean a Fire/Ghost type? Fire types are well known for their insane power and ghost types are known for their cunning moves. When you have that combined you get real awesomeness xD.