>>22038957252 Atk Mega Absol Play Rough vs. 252 HP / 252+ Def Mega Sableye: 136-160 (44.7 - 52.6%) -- 22.7% chance to 2HKO
252 Atk Sableye Dynamic Punch vs. 0 HP / 0 Def Mega Absol: 248-292 (91.5 - 107.7%) -- 43.8% chance to OHKO
One of them can OHKO the other alright.