Well, since Naruto is dressed predominantly in orange, I am forced to think of pumpkins and what other classic Halloween monster could I envision but the Headless Horseman wearing a pumpkin for his head.
After the transformation, Naruto would roll up to battle on a massive black steed. He would be dressed mostly in black except for orange trimmings about his longcoat and cape and naturally his vibrant orange pumpkin head. The pumpkin head would not have a green stalk however. It would have Naruto's trademark hairdo protruding skyward.
After dismounting, Naruto's powers would become evident. He leaps straight up and his pumpkin head detaches. His body lands first and he then makes a small jump back up in time to kick his descending pumpkin head at his opponent (which deals good damage by the way).
He would have other similar moves such as quickly ducking and stepping back which leaves his pumpkin head hovering until he blasts it forward at his opponent with a thunderous punch.
A battle-ending move would be him leaping into the air over a downed and nearly defeated opponent to do spinning flip of which the last revolution smashes the pumpkin head down onto the opponent for the win.
After such stunts, he quickly holds up his hands to the sides of his nonexistant head and a blast of yellow-orange light occurs between them resulting in the formation of a new pumpkin head.
