+1 252+ Atk Tough Claws Mega Charizard X Flare Blitz vs. 252 HP / 252+ Def Sableye: 265-313 (87.1 - 102.9%) -- 18.8% chance to OHKOCharX and Talonflame do well in the face of sable because they cannot be burned, something that azu cannot say.
CharX in particular is bulky enough to gain a turn to set up, what are the calcs on a +1 252+ atk Flare Blitz on this thing?
Not even a guaranteed OHKO. CharX has to be careful about a possible Foul Play:
+1 0- Atk Sableye Foul Play vs. 0 HP / 0 Def Mega Charizard X: 234-276 (78.7 - 92.9%) -- guaranteed 2HKO
Though I'm not sure how much bulk the usual CharX runs.