Rhyhorn claims an area with over a six mile radius as its territory. It apparently forgets where this territory is when running, however.
Once it starts running, it won't stop—even if it crashes through boulders. This disposition is what's caused its habitat to expand.
Ludicrously strong—when it butts heads with a mountain, it is the mountain that shatters. But its short legs struggle with turns, and it is incapable of stopping unless it collides with something.