I still don't understand why you want to ban something that noone is playing, namely Kyu-W. I saw near to zero Ice mono when laddering, and even when I faced it, it didn't prevent me from winning (I mean, it wasn't an auto-lose). This thing is absolutely not Overcentralizing, and in my opinion not overpowered. If your point is that you have to sac something whenever it enters in the field, I should answer : so does Specs Keldeo against most Monotype.
Furthermore, currently playing with a mono-water, I obviously have a hard time each time I faced a mono-grass (which doesn't even carry Skymin half of the time while they practically always run MVenusaur and Breloom). And I have to say that the one giving me trouble is far from being Skymin, but Mega-Venusaur. (this doesn't mean MVenu deserve a ban at all) Once again, I never played Skymin, and I didn't play a lot of team either, the only other one I made was a Poison one and was also able to kill it. I don't say that because I didn't have trouble with Skymin, it doesn't deserve a ban, but I won't be as straight-out as you are.
I'm not really fan of a Mega-Bro ban (because it can't solve the problem I have with Kyu-B in fact :/), but I didn't play enough battles in ORAS to make an idea (even if the few times I faced it, I easily get through it, but may be it is because I run a Quag so it's not a good agument).
Under no circumstances should usage be brought up as an argument against something being broken. As for Kyu-W being legitimately broken there have been extensive arguments that hold a lot of water in the previous pages.