I think you're a little ill-informed on a couple of things.I'm not really one to get heavily involved in stuff like this, but I'd like to try and convince those who have not yet voted, or those who are planning on getting reqs to vote, to not ban Kyurem-Black.
There's always been a lot of speculation about the fate of Kyurem-Black in the 1v1 metagame. It can be argued that Kyurem in the current meta has simply adapted far too well to any threat, and can pull off a set to eliminate what could be seen as any "hard counter". For example, Kyurem can utilize a few rather niche sets such as Haban Berry to lure and beat opposing Kyurem and Charizard-Mega-X, Groundium-Z can be for fat steels such as Heatran and Magearna, Roseli berry for offensive Mimikyu, Weakness Policy for Mega-Gyarados, and the list goes on.
Kyurem-Black does offer extreme versatility and can indeed put a strain on teambuilding when trying to cover for every single possible set. There's no denying that you're never going to be able to have a good team that can cover literally ever single one of Kyurem's sets. But is this really enough to warrant a ban? Versatility does not instantly account to broken, or unhealthy. While one set might beat a specific threat, it then loses to so many others. Kyurem on paper seems like its a broken mon, but in reality there's far more consequences to banning Kyurem rather than keeping it.
Kyurem is meta glue. It is the center of the metagame and as a result is extremely influential in practically every aspect of 1v1, from teambuilding (including custom spreads) to the ps ladder to tournament gameplay. Considering the current metagame and the suspect ladder, Kyurem is needed for metagame stabilization. The current metagame without Kyurem allows an extremely rapid influx of suddenly many more viable mons. To name a few, there's Golem, Donphan, Dragonite, Magnezone, Mimikyu, Tapu Koko, Landorus-Therian, Greninja, Jumpluff, Whimsicott. While a standard kyurem can't beat every mon mentioned here, its presence alone is enough to keep back a lot of mons from suddenly jumping up and becoming the new dominating figures of the metagame, notably Dragonite.
While I do believe that a suspect for Kyurem was needed, I don't believe that now is the right time for it, let alone a ban. We're barely less than a month away from ultra sun and moon, which is going to potentially introduce game changing mechanics and completely new pokemon to shake up the meta. Yet, despite being so close to a new meta, people want to ban the central figure of 1v1 and free a bunch of new threats? If this is done, the metagame won't stabilize at all before ultra sun and moon is released. We'd be leading one unstable meta into another. Banning Kyurem now doesn't make sense. I don't see the point. Keep Kyurem for now, test again down the track once the metagame has settled and stabilized to what ultra sun and moon has given us.
tl;dr = save Kyurem-Black. If there's a time to ban it, it's not now.
"For example, Kyurem can utilize a few rather niche sets such as Haban Berry to lure and beat opposing Kyurem and Charizard-Mega-X, Groundium-Z can be for fat steels such as Heatran and Magearna, Roseli berry for offensive Mimikyu, Weakness Policy for Mega-Gyarados, and the list goes on."
Fun fact: Kyurem-B has such goddamned good stats it can run enough bulk to live opposing Kyub and Charizard X's Outrages without the need for Haban Berry while OHKOing them with a Banded Outrage (or Specs Draco, Subzero, etc). Heatran loses to most non-Scarfed Kyurems without needing to resort to Groundium Z. As with the dragon types, Kyurem can run a physically defensive Choice Band to tank and OHKO Mimikyu.
Secondly, you didn't mention the real reason that Kyurem is broken: unpredictability. The argument that you did touch on, in that it has next to no counters, is not to be used as a stand-alone argument. Rather, the fact that A) you can't tell what set Kyurem is at team preview, B) that its sets beat different things, C) Kyurem's niche sets see some usage (1/3 Kyurems aren't running Scarf or Icium) and D) Kyurem has only a small handful hard counters (and most of them have to run off-meta sets to truly counter it) can lead us to this conclusion: that Kyurem-B is impossible to reliably win against unless you happen to be running one of its few counters. In short: it makes you lose when you should have won unless you start running Mega Metagross or Terrakion on all of your teams, which is obviously unfair and uncompetitive.