I feel like Kyurem-B is more intimidating on paper than it is in practice because of 170 base Attack and nasty STABs. Its Outrage and even its Dragon Claw really, really hurt. Not to mention it's bulkier than it should be and 120 base Special Attack compliments its base Attack really well.
But in matches, even with my goofy-weird teams (I'm a Crobat fanboy... don't hurt me), it never really poses as much of a threat as I expect. Sure, if you let it set up with Hone Claws or Sub, it can get a little scary if you don't have anything faster. But over a third of the metagame IS faster with super effective shots on it (no thanks to its defensively horrendous typing) and a lot of Pokemon below it speed-wise have super effective priority. Also, I can think of Pokemon who can set up that are just as scary if not scarier, and not all of them are even close to being top-tier threats (Haxorus w/ Dragon Dance or Swords Dance, Metagross with Agility, CM or TR Reuniclus)... Hone Claws just isn't that great of a set-up move, and Substitute... well, it's scary behind a sub, but even Pokemon like Toxicroak and regular Kyurem can set up shop and go to town when they're behind subs. Maybe not as immediately intimidating, but certainly they use subs well.
It absolutely punches holes in teams with Choice Band, Life Orb, or Expert Belt, but so do a lot of other Pokemon, and it doesn't even do so overwhelmingly. It can revenge kill with a Scarf, but there's things that are faster and not weak to all three entry hazards that can do the same. Its need to either split EV's on the mixed sets or forgo Attack for SpAttack (or vice versa) doesn't do it many favors. A very shallow USEABLE movepool makes it a bit predictable, and lacking physical Ice-STAB is just one of several problems that keep it from being a broken force. Middling speed, lack of set-up options, defensive typing that is easily taken advantage of, and lack of coverage (okay, maybe it doesn't really NEED coverage with Dragon- and Ice-type STAB coming off of 170 Base Attack and 120 Base Special Attack) hurt it.
I think it's very good at what it does, and it deserves its place around A or A+ on the viability thread, but it's something for which most mindful battlers will be prepared. It has checks and counters. It CAN be played around, and it doesn't take an exorbitant amount of effort or team dedication to do so. It'll wreck your house once in a while, but I doubt there's an experienced battler in here that hasn't been mauled at least once by every offensive Pokemon in OU. When it's used well, it'll earn its keep on your team. When it's not, you'll get smashed. Seems like a pretty good standard for any Pokemon in any slot on your lineup.
Feels like a lot of these arguments are going around in circles >.<
I agree with most of these points, and I think this post helps show how easily it kills stall. The great bulk and lack of quad weaknesses help it easily set up on defensive pokemon, and its wallbreaking capabilities are amazing. As I said before, the only things that can sort of wall it are Chansey and Cresselia in Sun. I just hate how it just massacres stall and defensive pokemon, making the metagame just so much more offensive, more so than most other pokemon. However, I disagree that it can be 'Played around' when playing stall, as the only thing you can do is predict perfectly and hope you have TS and get them up before it comes in. Alternately, you can try to get lucky and get hazards up and phaze it a lot, but it can easily 2HKO almost anything, making it hard to phaze.