Some of the best potatoes to make on the grill...chop up about 5 medium sized potatoes, 1yellow onion and throw it in a tin foil packet. Put some butter, salt, pepper, drizzle of olive oil, and sprinkle the top with chopped garlic out of a jar (a lot of garlic is good IMO). Seal that packet up and put it on indirect heat on the grill. Give it 20-30 depending on heat and amount of ingredients and enjoy some deliciousness. Direct heat can be used for some browner/crispier potatoes. My old lady loves this recipe.
I do that one all the time. It makes awesomely awesome taters.