Kyurem-B is only OU for its movepool. The only Physical moves it's going for is only Fusion Bolt and Dragon STAB. It has to rely on the Special side to get the coverage it needs, Hidden Power of your choice, Ice Beam, etc.
Unlike to it's counterpart Kyurem-W, it already has perfect coverage in its STABS alone. Even Heatran can't be countered since it has Turboflame?
Also, back in BW1, Blaziken and Excadrill were real threats(When i first played, Exca, Deo-S, Thundy-T were still in OU). Blaziken with SD and Speed Boost is pretty killer and nothing would appreciate a Sun Boosted +2 Flare Blitz. In Excadrill's case, it was banned since it was huge threat in the Sand and the only way to kill an Excadrill is basically, an Excadrill itself.
Atleast it wasn't Skymin flinching everything in OU. Darkrai Dark Voiding OU.