Well its true that Kyurem-B gets all that power and that usable SpAtk, but his main problem is just his speed and his typing. Thats all he mainly faces due to the fact that other threats can bypass him. I mean he gets that awesome attack, but his physical movepool is horrible. I mean Fusion Bolt, Dragon Claw, and Outrage isnt enough. Well although he gets Dragon Tail and Hone Claws, theres no way he could do this because of his typing, because fighting types and opposing faster types could already kill it, That being said, even Zekrom is better than Kyurem-B because of its better typing. Although Zekrom has a lower attack, his typing is way better. He doesn't seem A rankish, like i said, common threats can easilly pulverize him. He should be like B rank or B+ rank, because there are better Dragon types out there.
Well its true that infernape wad useful in certain situations. But one shouldnt overlook him, hes that powerful and can check on many threats. Speed tying with terrakion is certainly a niche because it allows infernape to bypass it in a 50% chance unlike most pokes, who dont do as well. Infernape's movepool is high, so that he can litterally take on threats WITHOUT the possibility of getting walled. Don't get me wrong, but infernape has so many options that he can come unexpected. His power of being a wallbreaker or a choice band user is that powerful. Even Blissey can't handle Infernape. Infernape can take on Forretress, Ferrothorn, and Skamory WITHOUT setup unlike others. Infernapes function of attacking is unique, because hes mostly an All-out-attacker. Thats his main job, while others are setup sweepers. Thay being said, he should AT LEAST be a B rank, or a B+ rank.