Mega Metagross has counters. I think it's best whenever we talk about it to assume the most coverage it has on it at one time is the Hammer Arm/Grass Knot/Dual Stab set. This set annoys the crap out of me because i can't throw Hippo, Slowbro, or (the suprisingly fat) Starmie. Starmie actually surprised me :C. i tried to use it as an offensive check but then got trounced by Grass Knot. Rotom w can check, but can't switch in. Also Refresh sets troll it. Defensive lando t is a check that only works if metagross has already mega evo'd, scarf lando t i would consider a limited check, barely above rotom-w. Quagsire is destroyed by GK, and ferrothorn by hammer arm. Mega Sableye is 2HKO'd by meteor mash, Manetric can't knock it out with guarenteed w/ overheat and is destroyed if it hasn't mega evolved yet, taking over 80-90% from Zen headbutt. Please don't list these. Defensive Scizor shuts it down. Counter Skarmory shuts it down. Alomomola Shuts it down. It's not uncounterable. The main problem with this pokemon is how annoying it is to kill without a strong defensive stop or sacking something (which doesn't even guarantee a trade, infact, usually doesn't). It limits balance building and is a nightmare to face on offensive because of how bulky, fast and strong it is. It's nearly impossible to knock out with a scarfed Revenge Killer. Keldeo Can't, Terrakion Can't, a bunch of other things can't. (too lazy to list). It's not overly broken but it's combination of superb defensive typing, good coverage, speed, bulk and strong power make it just barely overwhelming in OU. This thing is nowhere near as broken as Khan, Mence, Mawile or even Greninja.
Please god stop with these comparisons/asking for those to come back. Playing with and against it this pokemon is a massive asset to offensive and balance teams that has little reason not to use, and doesn't require much team support if at all. It's just too good to pass up using. The only megas i can really justify using over it are diancie, sableye, altaria and lopunny because they all occupy solid, strong niches that nothing else is in. And even then Mega Metagross is easily a superior team asset. The Opportunity cost for using this pokemon is just too good, albeit not overwhelming enough to kill diversity (think Mence/Khan), and not Aegis level. It's just too much for OU. Ciao mega metagross, sorry
-Clone- , but i'm going for Ban.
Also don't go on this rant about "if you ban this something else will be broken", or "Fairies will be OP no ban" For the latter, Fairies weren't OP before, and certainly won't be when it's gone. Too many steel types in the tier for it to be good, and it's not an amazing attacking type to begin with. As for the Former, the only pokemon who benefit from this ban are the fairies and Pinsir/Terrakion, none of which were broken before hand and won't be broken afterwards. Altaria isn't broken, Diancie isn't broken, and Clefable isn't broken. This meta will be actually quite stable after it's gone.
Luckstard. pokemon like clefable, altaria and diancie certainty won't be broken when it's gone. Clefable wasn't broken before hand, altaria loses to most fairies and walls that can phase it or just tank the 3 attacks set, and diancie is so frail and hard to set up (thinking of rock polish) not to mention almost every offense team carries priority like azumarill or scizor it's never going to be broken unless we ban like every steel/decent wall/priority user. Honestly, if you can't deal with these pokemon without mega metagross, you're bad at teambuilding. (and don't complain about your other stops being trappable, thats complaining zard x is broken because goth can trap your hippowdon.)