Physical - 244 HP

252+ Atk Triage Revenankh Drain Punch vs. 244 HP / 0 Def Mandibuzz: 96-114 (24.4 - 29%) -- 99.6% chance to 4HKO

252+ Atk Spell Tag Revenankh Poltergeist vs. 244 HP / 0 Def Mandibuzz: 84-99 (21.4 - 25.2%) -- 0.1% chance to 4HKO

+1 88 Def Zamazenta Body Press vs. 244 HP / 0 Def Mandibuzz: 130-154 (33.1 - 39.2%) -- 99.9% chance to 3HKO

+3 88 Def Zamazenta Body Press vs. +2 244 HP / 0 Def Mandibuzz: 109-129 (27.8 - 32.9%) -- guaranteed 4HKO -> Note that it can still Tera Fire or Roar to beat you

252 Atk Zamazenta Close Combat vs. 244 HP / 0 Def Mandibuzz: 153-181 (39 - 46.1%) -- guaranteed 3HKO

252 Atk Zamazenta Stone Edge vs. 244 HP / 0 Def Mandibuzz: 170-202 (43.3 - 51.5%) -- 6.6% chance to 2HKO

252 Atk Great Tusk Close Combat vs. 244 HP / 0 Def Mandibuzz: 163-193 (41.5 - 49.2%) -- guaranteed 3HKO

252 Atk Protosynthesis Great Tusk Close Combat vs. 244 HP / 0 Def Mandibuzz: 211-250 (53.8 - 63.7%) -- guaranteed 2HKO -> Burn avoids 2HKO

252 Atk Great Tusk Ice Spinner vs. 244 HP / 0 Def Mandibuzz: 146-172 (37.2 - 43.8%) -- guaranteed 3HKO

252 Atk Protosynthesis Great Tusk Ice Spinner vs. 244 HP / 0 Def Mandibuzz: 190-224 (48.4 - 57.1%) -- 91.8% chance to 2HKO -> Burn avoids 2HKO

252 Atk Wellspring Mask Ogerpon-Wellspring Ivy Cudgel vs. 244 HP / 0 Def Mandibuzz: 153-181 (39 - 46.1%) -- guaranteed 3HKO

252 Atk Wellspring Mask Tera Water Ogerpon-Wellspring-Tera Ivy Cudgel vs. 244 HP / 0 Def Mandibuzz: 204-242 (52 - 61.7%) -- guaranteed 2HKO -> Dicey, but if you see this you can Beak Blast into Sucker Punch to kill it

+2 0 Atk Snaelstrom Razor Shell vs. 244 HP / 0 Def Mandibuzz: 127-150 (32.3 - 38.2%) -- 97.9% chance to 3HKO

+2 0 Atk Snaelstrom Facade (140 BP) vs. 244 HP / 0 Def Mandibuzz: 158-186 (40.3 - 47.4%) -- guaranteed 3HKO

252 Atk Life Orb Ceruledge Bitter Blade vs. 244 HP / 0 Def Mandibuzz: 153-183 (39 - 46.6%) -- guaranteed 3HKO

252 Atk Ceruledge Bitter Blade vs. 244 HP / 0 Def Mandibuzz: 118-141 (30.1 - 35.9%) -- 40.7% chance to 3HKO

252 Atk Choice Band Dragapult Dragon Darts (2 hits) vs. 244 HP / 0 Def Mandibuzz: 192-228 (48.9 - 58.1%) -- 99.6% chance to 2HKO

+2 0 Atk Gliscor Facade (140 BP) vs. 244 HP / 0 Def Mandibuzz: 158-187 (40.3 - 47.7%) -- guaranteed 3HKO

252+ Atk Pixilate Tera Fairy Hemogoblin Extreme Speed vs. 244 HP / 0 Def Mandibuzz: 312-368 (79.5 - 93.8%) -- guaranteed 2HKO -> You can potentially revenge kill a weakened unboosted Hemogoblin with Beak Blast
+1 252+ Atk Dragonite Ice Spinner vs. 244 HP / 0 Def Mandibuzz: 242-286 (61.7 - 72.9%) -- guaranteed 2HKO

+2 252+ Atk Supreme Overlord 5 allies fainted Kingambit Iron Head vs. 244 HP / 0 Def Mandibuzz: 364-430 (92.8 - 109.6%) -- 56.3% chance to OHKO -> Yikes, but at least you can burn it - if you live it's a Roost vs Sucker Punch 50/50

+2 252+ Atk Supreme Overlord 5 allies fainted Tera Fire Kingambit Iron Head vs. 244 HP / 0 Def Tera Fire Mandibuzz: 182-215 (46.4 - 54.8%) -- 64.5% chance to 2HKO -> You might just kill it in this situation though (see Offensive Calcs)
Physical - 212 HP (changed matchups)
None really lol
Special - 244 HP

0 SpA Slowking-Galar Sludge Bomb vs. 244 HP / 0 SpD Mandibuzz: 127-150 (32.3 - 38.2%) -- 97.9% chance to 3HKO

0 SpA Slowking-Galar Ice Beam vs. 244 HP / 0 SpD Mandibuzz: 170-200 (43.3 - 51%) -- 5.9% chance to 2HKO

0 SpA Gholdengo Make It Rain over 2 turns vs. 244 HP / 0 SpD Mandibuzz: 332-392 (84.6 - 100%) -- 0.4% chance to 2HKO

252 SpA Gholdengo Make It Rain vs. 244 HP / 0 SpD Mandibuzz: 240-283 (61.2 - 72.1%) -- guaranteed 2HKO

0 SpA Pecharunt Malignant Chain vs. 244 HP / 0 SpD Mandibuzz: 117-138 (29.8 - 35.2%) -- 17% chance to 3HKO

252 SpA Pecharunt Malignant Chain vs. 244 HP / 0 SpD Mandibuzz: 151-178 (38.5 - 45.4%) -- guaranteed 3HKO

0 SpA Equilibra Doom Desire vs. 244 HP / 0 SpD Mandibuzz: 232-274 (59.1 - 69.8%) -- guaranteed 2HKO

252+ SpA Equilibra Doom Desire vs. 244 HP / 0 SpD Mandibuzz: 307-363 (78.3 - 92.6%) -- guaranteed 2HKO

0 SpA Shox Volt Switch vs. 244 HP / 0 SpD Mandibuzz: 194-230 (49.4 - 58.6%) -- 99.6% chance to 2HKO

0 SpA Shox Discharge vs. 244 HP / 0 SpD Mandibuzz: 222-264 (56.6 - 67.3%) -- guaranteed 2HKO

172 SpA Iron Crown Tachyon Cutter (2 hits) vs. 244 HP / 0 SpD Mandibuzz: 180-212 (45.9 - 54%) -- 46.2% chance to 2HKO

252 SpA Choice Specs Iron Crown Tachyon Cutter (2 hits) vs. 244 HP / 0 SpD Mandibuzz: 284-336 (72.4 - 85.7%) -- guaranteed 2HKO

252 SpA Choice Specs Dragapult Draco Meteor vs. 244 HP / 0 SpD Mandibuzz: 319-376 (81.3 - 95.9%) -- guaranteed 2HKO

252 SpA Darkrai Ice Beam vs. 244 HP / 0 SpD Mandibuzz: 244-288 (62.2 - 73.4%) -- guaranteed 2HKO

252 SpA Deoxys-Speed Ice Beam vs. 244 HP / 0 SpD Mandibuzz: 192-226 (48.9 - 57.6%) -- 96.1% chance to 2HKO

252+ SpA Life Orb Deoxys-Speed Focus Blast vs. 244 HP / 0 SpD Mandibuzz: 182-214 (46.4 - 54.5%) -- 59% chance to 2HKO

76+ SpA Hoopa-Unbound Thunderbolt vs. 244 HP / 0 SpD Mandibuzz: 286-338 (72.9 - 86.2%) -- guaranteed 2HKO

+2 252 SpA Chuggalong Clanging Scales vs. +1 244 HP / 0 SpD Mandibuzz: 273-322 (69.6 - 82.1%) -- guaranteed 2HKO -> lol
Special - 212 HP (changed matchups)
None