This thread is going in circles.
Kyurem-B is an excellent Pokemon. It boasts numerous advantages over its attacking brethren, including massive bulk and 170/120 offensive stats with moves like Ice Beam, Draco Meteor, Outrage, Fusion Bolt, Earth Power, Hidden Power Fire, Roost, Substitute, Dragon Claw, Hone Claws, and Dragon Tail to utilize them. Any attempts to call this movepool bad are futile. Keldeo has less viable moves than it, yet we consider it top-tier OU. With this movepool, it can run numerous sets, among which are Sub Hone Claws Dragon Tail, Modest lure with Focus Blast, Scarf, Band, specially based mixed, physically based mixed, Roost 3 attacks, and Sub 3 attacks. With a Babiri or Chople Berry, it becomes the best SmashPass recipient in the game. It functions as a counter to non-Analytic Starmie, Rotom-W, and Jolteon, and is a great check to Water- and Electric-types in general. The most devastating set is generally regarded to be Sub 3 attacks. This set is the bane of stall, as it has the coverage and sheer power to break apart the bulkiest of Pokemon, forcing stall teams to adapt with Pokemon like Jirachi, bulky SD Scizor, Stoutland and Breloom. With a Sub up, offensive teams are hard pressed to defeat it without losing a Pokemon in the process. Just describing the Sub set ignores the revenge killing abilities of the Scarf set, lucrative power of the Band set, etc. Kyurem-B has the ability to wreck its checks with the switch of a single move, making it brutally difficult to deal with and unpredictable.
On the other hand, Kyurem-B also has its fair share of weaknesses; chiefly, a vulnerability to hazards. Its Ice typing leaves it weak to Stealth Rock and vulnerable to Spikes. Toxic Spikes make it impossible for the Sub set to properly do its job. Kyurem-B is also weak to common priority, including Scizor's Bullet Punch and Breloom/Conkeldurr's Mach Punches. Weaknesses to common Fighting-, Rock-, and Dragon-type attacks limit its performance. The ever-common Jirachi is an excellent check to it, and with the most recent innovation -- a Shuca Berry -- Kyurem-B has a difficult time against it. As many Pokemon as Kyurem-B can beat, there numbers a sizable amount that it cannot hope to function in the presence of. Attacks like sun-boosted Fire-type attacks are too much, even for a Pokemon with such great bulk as Kyurem-B.
In summary, Kyurem-B is a top-tier, deadly threat. Arguing that would be futile. However, it has a number of flaws that somewhat limit its performance. Are they enough to counterbalance its sometimes overpowering strengths? That's the primary question I find needs to be addressed in this thread.
tl;dr focus on the important things, not random irrelevant stuff