Pumpkin Head vs Groot

Versus

Earth's Mystical Demon vs Alien Treeman who trumps?

Groot.

I am groot

Pumpkin pie anyone?

Pumpkinhead cannot withstand the power that is Groot

Pumkinhead is a demon. Groot may contain him. I don't see Groot KO'ng him.

If I recall correctly, the summoner/host of Pumpkinhead will become Pumpkinhead after the necessary people are dead, and then will be at rest.