Money is power and Scrooge could simply invest in some heavy artillery to destroy the Grinch. However, the Grinch is a creative and sly creature who would use some form of guerilla warfare to pounch on Scrooge.
It may come down to which character has more pent up anger. I'm going with the Grinch. At least Scrooge was part of civil society. The Grinch completely isolated himself atop that hill. Plus, that hill is a perfect homebase from which to fight.
