Um, actually, Bellibolt is currently in the Rarely Used Tier of Smogon's Tiering System, so actually, Bellibolt is a very mid Pokemon.
252+ Atk Choice Band Tera Bug Lokix Leech Life vs. 252 HP / 252+ Def Bellibolt: 186-220 (44 - 52.1%) -- guaranteed 2HKO after Stealth Rock