For a lot of these calcs, I'm going with a +2 Kingambit with 2 fainted allies since Swords Dance is really easy to get off with a sub and I usually bring King in during the middle/end of the game (at least 1 fainted ally usually).

252 Atk Great Tusk Earthquake vs. 112 HP / 0 Def Tera Grass Kingambit: 70-83 (18.9 - 22.4%) -- guaranteed 2HKO on Substitute

+2 252+ Atk Supreme Overlord 2 allies fainted Tera Grass Kingambit Tera Blast vs. 0 HP / 4 Def Great Tusk: 560-660 (150.9 - 177.8%) -- guaranteed OHKO

+2 252+ Atk Supreme Overlord 2 allies fainted Tera Grass Kingambit Tera Blast vs. 252 HP / 252+ Def Great Tusk: 422-498 (97.2 - 114.7%) -- 81.3% chance to OHKO

252+ Def Garganacl Body Press vs. 112 HP / 0 Def Tera Grass Kingambit: 82-97 (22.2 - 26.2%) -- 37.5% chance to break a Substitute

+2 252+ Atk Supreme Overlord 2 allies fainted Tera Grass Kingambit Tera Blast vs. 252 HP / 252+ Def Garganacl: 422-500 (104.4 - 123.7%) -- guaranteed OHKO

252+ Def Dondozo Body Press vs. 112 HP / 0 Def Tera Grass Kingambit: 75-89 (20.3 - 24.1%) -- guaranteed 2HKO on Substitute

252+ Atk Supreme Overlord 2 allies fainted Tera Grass Kingambit Tera Blast vs. 252 HP / 252+ Def Dondozo: 234-276 (46.4 - 54.7%) -- 59% chance to 2HKO

+2 252+ Atk Supreme Overlord 2 allies fainted Tera Grass Kingambit Tera Blast vs. 252 HP / 252+ Def Toxapex: 189-223 (62.1 - 73.3%) -- guaranteed 2HKO after Black Sludge recovery