So we're trying to find counters, now? I think the fastest way you're going to find a counter is if you examine everything that was already known to take a mence DM, then eliminate the stuff that gets destroyed by EQ.
The typical list of specs mence counters is "any sdef oriented steel, blissey, cresselia, or milotic." Cresselia has already been proven to give this set trouble, but for pokes like ttar and hera, that obviously doesn't matter. Bliss was already shot down, and pretty much any of the previously mentioned steels get blasted by EQ (except bronzong and skarm, neither of which like fire blast, and skarm tends to avoid sdef EVs, anyway). When Milo is used as a specs mence counter, it usually packs a ton of sdef, and doesn't leave much room left for defense, but since this obviously isn't specs mence, if milo was to run max HP and def (bold) it would take min 64%* (and max 75%*) from an SD'd quake, easily 2HKOing. That same milotic takes 45-53%* from chomp's DM (hey, it's no salamence, and it's no specs). A milo with no satk EVs does 332-392 damage (93-109%) to chomp with ice beam (assumes lonely). Milo might be a viable counter if you can get it in at the right time (aka before/when it SDs), although it would require quite a different EV spread from what you would usually use to counter specs mence (I don't care how good its sdef is - with max hp, no sdef EVs, and +sdef nature it takes the same amount as a max hp/max+ def one takes from chain chomp's EQ, so it will usually be KOed before it can recover; I guess you can't get the best of both worlds, although I'm not sure how many people used milo as a specs mence counter in the first place).
* calcuations marked with a star were done on nb, so the actual result may be slightly lower in DP (note this applies to all calculations done except for milo's ice beam on garchomp)