iirc it survives Power Whip from Ferrothorn 100% of the time. Actually I'll be honest with you, those EV's are not mine, I just used them because someone in my team had already used it, he said it survives Power Whip from Ferrothorn and it was such a great partner to Heracross.
So honestly, if you really want to try other EV combinations go ahead. Iirc making your subs survive Gyro Ball was not worth it. But making it survive 100% of the time against Power Whip sure does a lot to him. Ferrothorn is a smaller problem, as you have Focus Blast, but using him as setup fodder is great.
If you really want to, Blue Star was the one using it, you can ask him if there is any other reason for those EVs...