Vs garchomp
vs
252 Atk Garchomp Earthquake vs. 4 HP / 0 Def Volcanion: 282-332 (93.3 - 109.9%) -- 62.5% chance to OHKO
252 Atk Garchomp Earthquake vs. 4 HP / 0 Def Shuca Berry Volcanion: 141-166 (46.6 - 54.9%) -- guaranteed 2HKO after Stealth Rock
+2 252 Atk burned Garchomp Earthquake vs. 4 HP / 0 Def Shuca Berry Volcanion: 140-165 (46.3 - 54.6%) -- guaranteed 2HKO after Stealth Rock
252 Atk Garchomp Stone Edge vs. 4 HP / 0 Def Volcanion: 188-222 (62.2 - 73.5%) -- guaranteed 2HKO after Stealth Rock
They won't recklessly use a z without a boost
attacks
252 SpA Volcanion Steam Eruption vs. 0 HP / 4 SpD Garchomp: 205-243 (57.4 - 68%) -- guaranteed 2HKO
If you sack it burning it is a good thing since you save health on something like lando or tang
Vs landorus-therian
attacks
+2 252 Atk burned Landorus-Therian Earthquake vs. 4 HP / 0 Def Shuca Berry Volcanion: 151-178 (50 - 58.9%) -- guaranteed 2HKO
252 Atk Landorus-Therian Earthquake vs. 4 HP / 0 Def Shuca Berry Volcanion: 153-180 (50.6 - 59.6%) -- guaranteed 2HKO
252 Atk Landorus-Therian Stone Edge vs. 0 HP / 0 Def Volcanion: 204-240 (67.7 - 79.7%) -- 37.5% chance to OHKO after Stealth Rock
+2 252 Atk burned Landorus-Therian Supersonic Skystrike (175 BP) vs. 4 HP / 0 Def Volcanion: 264-312 (87.4 - 103.3%) -- 25% chance to OHKO
If they try to predict, but usually they won't waste a flyinium on you tho :)
attacks
252 SpA Volcanion Steam Eruption vs. 252 HP / 0 SpD Landorus-Therian: 434-512 (113.6 - 134%) -- guaranteed OHKO
Clean OHKO (different spread to inform that even in the worst likely scenario you can do so)
vs Heatran
attacks
252+ SpA Heatran Earth Power vs. 4 HP / 0 SpD Shuca Berry Volcanion: 118-139 (39 - 46%) -- guaranteed 2HKO after Stealth Rock
252 SpA Heatran Earth Power vs. 4 HP / 0 SpD Shuca Berry Volcanion: 107-127 (35.4 - 42%) -- 80.1% chance to 2HKO after Stealth Rock
252 SpA Heatran Bloom Doom (190 BP) vs. 4 HP / 0 SpD Volcanion: 226-267 (74.8 - 88.4%) -- 93.8% chance to OHKO after Stealth Rock
252+ SpA Heatran Bloom Doom (190 BP) vs. 4 HP / 0 SpD Volcanion: 249-293 (82.4 - 97%) -- guaranteed OHKO after Stealth Rock
Again they won't recklessly click the z here. Also both natures are viable to run so yeah
attacks
252 SpA Volcanion Steam Eruption vs. 252 HP / 136+ SpD Heatran: 276-326 (71.5 - 84.4%) -- 18.8% chance to OHKO after Stealth Rock
You don't always ko but you definitely leave it in range of something(different spread is due to same reason as lando situation above)