Yes, they are very good at hill climbing. The only bad thing is, they will easily hit the powerband and pop wheelies on hills. So just put it in 1st-2nd gear, and lean up. :)
You have to teach them Rock Climb, which is a HM(Hidden Move).
So he could write to the other side
12.5-mile long with 156 turns along the way.
Gravity keeps you from sliding backwards when you climb a hill. If there is no gravity you will fall of the hill.