I just ran the calcs on 252/252+ Rotom-W, a Jolly (216 EVs to outspeed, since everything else between base 86 and base 91 runs speed so you won't be beating them) +2 M-Mawile will OHKO with Play Rough as long as you have 92 or more Atk EVs. That doesn't seem right, but I'll take the calculator's...