To follow up on this, (I whole heartedly agree with this post) I'd like to elaborate on Mega Heracross's ability to counterlead:
Nominating Mega-Heracross for B+ rank
Mega-Heracross has gained a lot of popularity lately, and for good reason. First and foremost, it is able to able to pretty much dismantle Stall without too much difficulty : the only common Pokemon on Stall that can avoid a 2HKO from it after Rocks are Gliscor, who loses to the SD variant since it can't to much more than Toxic stall Heracross, Max Defense Hippowdon who once again, can't do much back besides stall for a Pin Missile miss. This, added to the fact that stall teams don't really prepare for Mega-Heracross as much as they do for the likes of Landorus-I and Kyurem-B. A lot of stall teams have Skarmory as they most solid switch-in to it, even though it goes down from 2 Close Combats after rocks or very little prior damage (even more likely to 2HKO if they run Rocky Helmet over Leftovers).
Now, it may seem like Mega-Heracross is worse vs Offense than B+ rank megas such as Gardevoir and Medicham due to its low speed, but that really isn't true, since Mega-Hera has something few good stallbreakers have : good bulk. Mega-Heracross's solid defenses makes it relatively tough to properly check, and allows it to deal with offensive Pokemon that can cause a lot of trouble for offensive teams such as Bisharp, Excadrill, Weavile, Lucario, and Sash leads such as Breloom (can counter-lead and destroy it, even outspeeds if Adamant before mega), Mamoswine (same here, MHera does have to take a hit if it's Adamant and Mamo is Jolly but takes it decently), and Diggersby. Its bulk enables it to find opportunities to come in against offensive teams and threaten the opposing Pokemon, and nothing on offense really likes switching into Mega-Heracross. Pin Missile is not a hard move to spam, since a lot of things that resist it is either slower and gets picked off by a coverage move (like Azumarill, Aegislash or Mawile) or really doesn't take it that well despite the resistance (like Excadrill and Keldeo-by the way, you can easily give MHera a few HP EVs to live a Choice Specs Hydro Pump from Keldeo and threaten to OHKO back with Close Combat, that's how impressive its bulk is).
All in all, Mega-Heracross's ability to knock around Stall as well as deal with offensive teams decently make it a solid pick for offensive teams, and the fall of Birdspam makes it all the more viable in the current metagame. I therefore feel like it fits alongside Mega-Medicham and Mega-Gardevoir, as opposed to Conkeldurr and Lucario.
Once Deo-d/s is banned, the usual leads will probably simmer down to mamo/breloom/terrak/garchomp, and Mega heracross beats the crap out of all o them 1v1.
Breloom is simply outsped turn 1 and OHKO'd by pin missile, I used this baby on suspect and I cannot tell you how many brelooms just died turn 1 to this bad boy, it made me so happy ;_;
I generally like to run bullet seed>rock blast b/c my team doesn't really need the rock coverage and values hitting grounds harder; lando-t, gliscor, and mamo. Oh speaking of mamo:
252+ Atk Mega Heracross Pin Missile (5 hits) vs. 4 HP / 0 Def Mamoswine: 360-425 (99.4 - 117.4%) -- approx. 93.8% chance to OHKO
So unless mamoswine is jolly max speed, they will more than likely just die turn 1. Even if they are jolly, all they get up are rocks, and boy mamo is such a fuckin threat its really nice to get rid of it turn 1 and only have to pay rocks as a price.
As far as terrakion goes, all it usually does is get rocks up while bullet seed kills it, and garchomp is a bit bulkier so two pin missiles will take him down. Either way, you only die to a +2 outrage so atleast they won't get rocks up. Not to mention if garchomp leads that means its probably not scarfed, and that's great cuz scarf chomp is a bitch.
And if you run a pursuit bisharp to help get rid of aegislash, then that frees up a slot for SD>eq, which in my opinion is well well worth it.
SD heracross is SOOO much more threatening thatn 4 attacks its amazing. Lando-t and gliscor are no longer safe switch-ins, hell nothing is. Lando-t and gliscor don't even do anything back except a weak stone edge or a desperate toxic, as you mercilessly set up on their mega hera check and 2hko it. The best part is that mega hera blows apart usual stall mons that are meant to take on physical attackers, skarm+quag, as it 2hko's them both with CC.
Just watch out if skarm gets a free switch-in on mega hera and you're not boosted/its sturdy is intact, some still carry bb...
All in All this baby is a lovely mon with lovely forearms and deserves B+ for sure.