>>20919139+1 252+ Atk Aerilate Salamence Return vs. 4 HP / 252+ Def Eviolite Chansey: 486-573 (75.7 - 89.2%) -- guaranteed 2HKO
+1 252+ Atk Aerilate Salamence Double-Edge vs. 4 HP / 252+ Def Eviolite Chansey: 570-672 (88.7 - 104.6%) -- 31.3% chance to OHKO
+1 252+ Atk Aerilate Salamence Double-Edge vs. 0 HP / 0 Def Heatran: 204-241 (63.1 - 74.6%) -- guaranteed 2HKO after Leftovers recovery
+1 252+ Atk Aerilate Salamence Return vs. 0 HP / 0 Def Heatran: 174-206 (53.8 - 63.7%) -- guaranteed 2HKO after Leftovers recovery
+1 252+ Atk Aerilate Salamence Double-Edge vs. 244 HP / 28+ Def Gliscor: 316-373 (89.7 - 105.9%) -- 37.5% chance to OHKO
+1 252+ Atk Aerilate Salamence Return vs. 244 HP / 28+ Def Gliscor: 270-318 (76.7 - 90.3%) -- guaranteed 2HKO after Poison Heal
+1 252+ Atk Aerilate Salamence Return vs. 228 HP / 0 Def Azumarill: 441-520 (110.8 - 130.6%) -- guaranteed OHKO
+1 252+ Atk Aerilate Salamence Double-Edge vs. 228 HP / 0 Def Azumarill: 517-610 (129.8 - 153.2%) -- guaranteed OHKO
This is with 0 extra points added to attack. The OHKO would be nice on Chansey, but you're going to lose a ton of HP from it anyway. Return is going to be a better choice due to the negligible number of Pokemon you won't be able to 1/2HKO with it.
You also don't need to worry about Roost at all.
