Preheat your oven to 475°F. If you have a pizza stone, place it in the oven to heat.
In a medium bowl, mix the shredded chicken with buffalo wing sauce until well coated.
On a floured surface, stretch the pizza dough into a 12-inch circle or rectangle, depending on your preference.
Transfer the dough to a pizza peel dusted with cornmeal or parchment paper if using a pizza stone, or to a greased baking sheet.
Brush the dough lightly with olive oil, then sprinkle with garlic powder and black pepper.
Spread ranch dressing over the dough, leaving a small border for the crust.
Top the dressing with the buffalo chicken mixture, spreading it evenly.
Sprinkle the sliced red onion and shredded mozzarella cheese over the chicken, as well as the blue cheese crumbles if using.
Transfer the pizza to the preheated oven (or onto the pizza stone) and bake for 12-15 minutes, or until the crust is golden and cheese is bubbly.
Remove from the oven, let it cool for a couple of minutes, then slice and serve.