Banning Mega Mawile would be blind sighted in my opinion. It is banning based on stats rather than calculations and usage. Skarmory-heatran core beats it, as if it subs, you got out into skarm and continually roost, passively killing it with rocky helmet. Haze tentacruel beats it, living sucker punch, breaking the sub with scald, and then continually wearing it down, mixing in status moves for free recovery. Stall Zard X can beat it with 220+ defense, willoing it if it is sd mawile, or fire punch + roosting if it is sub punch. If gliscor already has its orb off, it can beat it 1v1. Mega Venusaur is a switch in when carrying eq, which is intelligent to do anyway due to heatran. Against HO, it's hardly ban worthy, as it is hard for it to set up before getting a free mega evolution, and gets ohko'd by garchomp, the zards, the landos, mamo, drill, and heatran. With any decent hit, hp fire greninja, tyranitar, specs keldeo, terrakion and medicham can finish it off. When the majority of OU pokemon can 2hko you(29 out of 47), and you are relatively predictable, you should not be banned IMO.
Edit: Also, it doesn't cause centralization issues since any faster WOW user can usually check it.
Edit: Also, it doesn't cause centralization issues since any faster WOW user can usually check it.