Semi-high rolls? Really? thats the best you can come up with? Really? Thats a 3HKO. Can you show what a crunch does after burn? I'd estimate about 35%, letting you drop a rest or pain split. I get the stealth rock, but did you even factor in eviolite as well? Btw, PUP doesn't affect dusclops. And a scrappy khan only gets +1. You should predict the PUP, switch in Clops, ignore PUP, burn, then pain split. Khan has no chance of a burn free kill.Dusclops and Cofagrigus are even less relevant in XY OU than Sableye. But to answer your question:
252+ Atk Parental Bond Mega Kangaskhan Crunch vs. 252 HP / 252+ Def Eviolite Dusclops: 114-135 (40.1 - 47.5%)
Between 53-60% after SR. With semi-high rolls that's a 2HKO. Cofagrigus takes it even worse obviously, but here's the calc anyway:
252+ Atk Parental Bond Mega Kangaskhan Crunch vs. 252 HP / 252+ Def Cofagrigus: 156-186 (48.7 - 58.1%)
Also, opposed to what you say, a burned Kangaskhan is not a dead Kangaskhan. Let me show you how much a burned Return does to defensive Rotom-W after a PuP:
+2 252+ Atk Parental Bond burned Mega Kangaskhan Return vs. 252 HP / 252+ Def Rotom-W: 183-216 (60.1 - 71%)
That's Max HP/max Def Rotom-W, and it still does 60% minimum. It's considerably less threatening when burned ofcourse, but don't consider it as a way to neuter Mega Kangaskhan completely. Keep in mind that Will-o-wisp only has 85% accuracy too, and missing it will quite frankly cost you the game a lot of the time against something like Mega Kangaskhan.
also dusclops is relevant because of scolipede. Curse is baton passed and hits around protect and substitute. It destroys any chance of scolipede baton passing to cause a sweep.