((Copy pasted the Rhyperior set with the EVs it has against the Salazzle, but I used standard EVs for Salazzle since I don’t know what EVs the Salazzle has, if any. Here’s what I got:
Lvl 40 252+ Atk Rhyperior Earthquake vs. Lvl 80 0 HP / 0 Def Salazzle: 252-300 (113 - 134.5%) -- guaranteed OHKO
Possible damage amounts: (252, 256, 256, 264, 264, 268, 268, 276, 276, 280, 280, 288, 288, 292, 292, 300)
))
*Now Rhypherior uses Smack Down to ground Haunter*