Place the chicken in the dish of a slow cooker, top with Buffalo sauce and toss to coat. Cover and set on low for 8 hours or high for 5 hours.
Once the chicken is cooked through and easily shreds apart between two forks, shred the chicken breasts and toss to coat it with the sauce.
Bake the sweet potatoes:
Preheat the oven to 425F and line a large baking sheet with parchment paper or aluminum foil. Gently give the sweet potatoes a good scrub with warm water to remove any debris or dirt and pat them dry with a kitchen towel.
Using a fork, prick the skin of each potato and rub them with olive oil. Place the potatoes on the prepared baking sheet and bake for 30 to 45 minutes, or until the center is cooked through and pierces easily with a fork. Remove the potatoes from the oven.
Assemble:
Slice each baked sweet potato lengthwise. Open and use a fork to separate the sweet potato meat from the skin. Fluff with a fork and make the opening wide.
Top the sweet potato with a generous amount of cooked buffalo chicken, drizzle with Ranch dressing, blue cheese crumbles, and sliced green onions (if using).