252+ Atk Unfezant Night Slash vs. 252 HP / 252+ Def Gourgeist-Large on a critical hit: 146-174 (41.2 - 49.1%) -- 19.1% chance to 2HKO after Stealth Rock and Leftovers recovery
Not only that, but colbur is common so it's even more cleanly cut a matchup.

Won't calc pidge because that one is kinda obvious with Brave Bird or Hurricane.

252 Atk Choice Band Fearow Drill Peck vs. 252 HP / 252+ Def Gourgeist-Large: 192-228 (54.2 - 64.4%) -- guaranteed 2HKO after Stealth Rock and Leftovers recovery

It does need band but yeah, it's something at least.