Wall for ~Skirmish~ (page 7)

252+ SpA Spectrier Shadow Ball vs. 0 HP / 4 SpD Hawlucha: 226-267 (76 - 89.8%) -- guaranteed 2HKO

252+ Atk Hawlucha Acrobatics (55 BP) vs. 0 HP / 0 Def Spectrier: 118-141 (34.6 - 41.3%) -- 5.9% chance to 2HKO

252 SpA Thievul Dark Pulse vs. 0 HP / 4 SpD Espeon: 206-246 (76 - 90.7%) -- guaranteed 2HKO

252 SpA Choice Specs Espeon Dazzling Gleam vs. 0 HP / 4 SpD Thievul: 280-330 (99.6 - 117.4%) -- guaranteed OHKO

https://m.bulbapedia.bulbagarden.net/wiki/Damage

This should be slightly clearer.

I don't really know if its only Staraptor or others but I'll try.
And here is a picture of the damage formula:
https://m.bulbapedia.bulbagarden.net/wiki/File:DamageCalc.png
Fight between Heracross-Mega and Choice Scarf Poliwrath:
252+ Atk Heracross-Mega Close Combat vs. 0 HP / 4 Def Poliwrath: 292-345 (90.9 - 107.4%) -- guaranteed OHKO
252 Atk Poliwrath Liquidation vs. 0 HP / 0 Def Heracross-Mega: 100-118 (33.2 - 39.2%) -- 99.8% chance to 3HKO

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