I am curious to hear what people have been using as their check/counter for Kyurem-B on offensive teams. Assault Vest Excadrill, Assault Vest Conkeldurr, and Roost (Mega) Scizor are the best that i have found, but Scizor is kinda easy to wall, and the other two are easy to wear down, but this usually isn't a problem as the games last only a few turns anyway. So, what i wanted to say is that i find myself using either one of those two mons (AV Conk and AV Excadrill) on my offensive teams, or making sure that almost all of my Pokemon can threaten it in some way.
Another extremely useful Pokemon to have against Kyu-B is DD Mega Ttar. DD Mega Tyranitar is the only sweeper that can directly take advantage of Kyurem-B and set up on it, taking only 33.9 - 40.3% from +SpA Kyu-B's Earth Power. It's also surprising how many offensive teams are DD Mega Ttar weak, especially those that rely on CB Talonflame as their revenge killer and have no Scarfer.
Thankfully, on the defensive end, Kyurem-B is much more manageable than it used to be. Sylveon, Clefable, Chansey, Mega Scizor, and Tyranitar are all great counters to Sub + 3 attacks Kyu-B, while physically defenisve Clefable and Sylveon can deal with almost any Kyu-B set in general, aside from CB Kyu-B' Fusion Bolt.
All in all, i find Kyu-B to be one of the most threatening Pokemon against both offense and defense, but it's quite manageable in this gen with proper teambuilding, as there are quite a few viable checks and counters to it (thx Assault Vest and Fairies!). It's also a positive presence in the metagame, as it checks extremely threatening / annoying Pokemon such as Manaphy, Greninja, Rotom-W, and Mega Venusaur, and is one of the very few Pokemon that can consistently break down Mega Venusaur and his defensive teammates.