I don't suppose there's any reason why you couldn't make dauphinoise in a slow cooker but, to be honest, i don't think it'd be too great. For a start, there's a greater risk of the cream splitting, and also you wouldn't get the crisp, browned layer on top. Using sliced, par-boiled potatoes layered in an oven dish is should only really take 30 mins at most in a hot oven.
Pork, however, is ideally suited to slow-cooking! As it has a tendency to dry out, a slow-cooker is the perfect way to cook it, especially with the cheaper cuts.