>>32008661MegaMence is really not as good as you try and make him out to be in the official formats, otherwise he would have been everywhere in VGC 2015 and he would be the undisputed King of Battlespot, but this is far from being the case.
You mention Ubers, a fanmade teir which uses the 6v6 format which allows you to cover for all of Mences weaknesses and thus allow him many opportunities to go and wreck, but you can't do that in 4v4 and 3v3, especially in 3v3, mons have far less support and they have to be able to stand on their own because they'll be facing a hell of alot more unfavourable match ups than they would in 6v6 due to having less teammates along with the reduced amounts of switching(this is why Stall doesn't work in the official formats), and there are more than a few mons who are better at doing that job than MegaMence, Garchomp for one, who has outclassed MegaMence in Battlespot since it first began.
MegaMence is strong, one of the best megas for sure, that I agree with, but broken in every format? Nope, that I heavily disagree with, he just doesn't have the necessary back up. Like another anon said earlier, the only mon who could possibly fall under being broken in the official meta atm is Tapu Lele. She has warped the meta entirely around her and her bullshit terrain and has fucked over alot of mons in the process, Mega Gengar probably being the biggest casualty (though losing Levitate, the prevalence of Scarfchomp and the nerf to Destiny Bond played a part in Gengars fall desu). I can't wait until shes nerfed in Gen 8, not even Mega Kanga was this bad ffs.