For all those looking for defensive answers to Mega-Khan, you can stop wasting your time -- there are none. Essentially, M-Khan can bypass any defensive threat with any number of very viable moves. I always think back to the banning of Deoxys-D in 5th gen for situations like this - yes Deo-D could get past any one of its counters with niche/borderline useless moves, but leaves it vulnerable to the other 10. With M-Khan, however, there's hardly even a need to think. The following set smashes through every single defensive check you can think of:
Kangaskhan (F) @ Kangaskhanite
Ability: Scrappy
EVs: 252 Atk / 4 SDef / 252 Spd
Adamant Nature
- Return
- Sucker Punch
- Power-Up Punch
- Earthquake/Fire Punch/Crunch
Earthquake is what I have been using since the beginning of the meta only a short while ago, and it's what has helped propel me not only to a #1 position in Pokebank, but to five other places in the top-100 with a number of alts. Of course, this doesn't mean much given the state of the ladder at the moment, but it can at least attest to the fact that I have a slight idea about what I'm talking about.
Earthquake leaves the door open for Trevenant and Gourgeist to come in and Will-o-Wisp it. Fire Punch or Crunch, on the other hand, not only beat those two Ghosts, but allow you to get past both Ferrothorn and Skarmory. In truth, I'm only still running Earthquake over one of the two alternatives because it bypasses the guessing game you face against Aegislash by choosing a contact move.
Rocky Helmet on any of the above also help keep M-Khan in check (and, in fact, is the only consistent way of beating the above set with any defensively-oriented Pokemon), but even then, Drain Punch is a viable option that can alleviate the recoil. Sableye can force M-Khan out or rely on the 85% chance to burn it, but even ghosts are hilariously taken care of by simply not Mega-Evolving on a predicted switch to one of them. Return from a regular Adamant Khan does upwards of 50% to defensive Sableye, forcing it to either Recover endlessly or try its luck to burn it, where the Khan user can easily just switch out. Not to mention the fact that a Scrappy Power-up Punch is super-effective against things such as Sableye and Aegislash (though, of course, do much less to a Sableye anyway).
With a ludicrously high number of defensive options typically seen in the metagame bested by M-Khan, what's left are offensive options, right? With 105/100/100 defensive stats, as well as 100 base speed, the only things that are able to reliably take on a M-Khan on their own offensively are those who are faster (or can take a +2 Return), can stomach a +2 Sucker Punch, and can hit it with a STAB, super-effective move. Unfortunately, with Blaziken deemed too powerful for the current meta, that's one less option to send in against a M-Khan once it gets +2 (which it can get on essentially every single thing it forces out). This leaves Lucario, the musketeers, Infernape (who takes 70% from a +2 Sucker Punch), and Mienshao (who takes 80%). It becomes even more centralizing in non-Pokebank OU, as you can only legally access Lucario and Meinshao at the moment. There might be some other niche options I'm neglecting to mention but the point is clear - if you're going to deal with M-Khan directly (rather than sacrificing multiple Pokemon to barrage it with enough priority to break its considerable bulk) you all but need one of a very small number of fast, offensive fighting types.
M-Khan is both way too powerful and way too bulky to be reliably handled by virtually the entire metagame, and uses everything that cannot OHKO or status it as set-up bait to begin its rampage through the rest of your team, which it can pretty easily sweep with a total of 3 moves. I think having a suspect test on it some months in the future is ignoring the devastating impact it already has on the metagame, and I believe it as worthy of a quick-ban as Blaziken -- if not even more worthy.