Porygon 2 Calcs
Offensive Calculations
100 SpA Porygon2 Ice Beam vs. 68 HP / 100 SpD Landorus-T: 168-200 (97.1 - 115.6%) -- 81.3% chance to OHKO

With +SpA Download/Electric Terrain
+1 100 SpA Porygon2 Ice Beam vs. 252 HP / 100 SpD Tapu Bulu: 112-132 (63.2 - 74.5%) -- guaranteed 2HKO after Grassy Terrain recovery
+1 100 SpA Porygon2 Ice Beam vs. 60 HP / 220 SpD Mega Salamence: 208-248 (116.8 - 139.3%) -- guaranteed OHKO
100 SpA Porygon2 Thunderbolt vs. 156 HP / 4 SpD Mega Charizard Y in Electric Terrain: 106-126 (61.2 - 72.8%) -- guaranteed 2HKO
100 SpA Porygon2 Thunderbolt vs. 252 HP / 0 SpD Tapu Fini in Electric Terrain: 96-114 (54.2 - 64.4%) -- guaranteed 2HKO

Defensive Calculations
252 Atk Kartana All-Out Pummeling (175 BP) vs. 244 HP / 108 Def Eviolite Porygon2: 166-196 (86.9 - 102.6%) -- 18.8% chance to OHKO
+6 252+ Atk Huge Power Azumarill Aqua Jet vs. 244 HP / 108 Def Eviolite Porygon2: 109-129 (57 - 67.5%) -- guaranteed 2HKO
252+ SpA Ludicolo Hydro Vortex (185 BP) vs. 244 HP / 52+ SpD Eviolite Porygon2 in Rain: 123-145 (64.3 - 75.9%) -- guaranteed 2HKO
52+ SpA Tapu Koko Gigavolt Havoc (185 BP) vs. 244 HP / 52+ SpD Eviolite Porygon2 in Electric Terrain: 127-150 (66.4 - 78.5%) -- guaranteed 2HKO
252+ SpA Mega Charizard Y Overheat vs. 244 HP / 52+ SpD Eviolite Porygon2 in Sun: 129-153 (67.5 - 80.1%) -- guaranteed 2HKO
252+ SpA Tapu Lele Shattered Psyche (175 BP) vs. 244 HP / 52+ SpD Eviolite Porygon2 in Psychic Terrain: 148-175 (77.4 - 91.6%) -- guaranteed 2HKO
252 Atk Tapu Bulu Bloom Doom (190 BP) vs. 244 HP / 108 Def Eviolite Porygon2 in Grassy Terrain: 157-186 (82.1 - 97.3%) -- guaranteed 2HKO after Grassy Terrain recovery
252 Atk Tough Claws Mega Metagross Iron Head vs. 244 HP / 108 Def Eviolite Porygon2: 63-75 (32.9 - 39.2%) -- 99.8% chance to 3HKO
252+ SpA Choice Specs Tapu Fini Moonblast vs. 244 HP / 52+ SpD Eviolite Porygon2: 66-78 (34.5 - 40.8%) -- guaranteed 3HKO
252+ Atk Landorus-T Earthquake vs. 244 HP / 108 Def Eviolite Porygon2: 51-60 (26.7 - 31.4%) -- guaranteed 4HKO

Without Eviolite
252+ Atk Landorus-T Superpower vs. 244 HP / 92 Def Porygon2: 160-190 (83.7 - 99.4%) -- guaranteed 2HKO