The Super Sized Prankster! (which is sadly not its Ability...)
Item: Focus Sash
Nature: Sassy or Relaxed
EVs: 252 Hp, 252 Sp. Def Or Def, 4 Atk
Will-O-Wisp, Flame charge, or Trick Room
Description: Personally, I love Gourgeist, I just can't get enough of the Litt- er... BIG pumpkin!.. (I mean, its super sized form can be 5''7', that's not short.) This moveset is built for taking down an opponents Pokemon via destiny bond, but having other options just in case, please note that this set works best on trick room teams. First, make sure there aren't any hazards on the field, then send in Gourgeist after an ally has been defeated. Use Will-O-Wisp (halves enemy attack) or Flame Charge (Raises Gourgeist's speed) or Trick Room (to ensure it and your other slow Pokemon go first), then, use destiny bond and either kill them or give a nice scare to your opponent if they switch out (they wouldn't risk attacking you, for fear of losing a Pokemon). Trick-Or-Treat is used as another strategy in adding Ghost to your opponent, then hitting them with a super effective Priority Shadow Sneak (Or you can add it to a dark type ally in making an 'almost' No-Weakness friend). So while Gourgeist isn't top of the class, or packed full of strategies... I found that the Lovely Big... or small, Pumpkin Pokemon, can still pull off a few tricks!