alexwolf
lurks in the shadows
While you do have a point that Yveltal's typing is kinda in the same boat as Kyurem-B's (SR weak, lots of common weaknesses, with Kyu-B being weak to Steel, Fighting, Rock, Dragon, and Fairy, while Yveltal is weak to Rock, Ice, Electric, and Fairy), Yveltal is much less prone to priority, as it is only weak to Ice Shard which is never Technician boosted, unlike Bullet Punch and Mach Punch, to which Kyu-B is weak to. So, considering Yveltal's great bulk, even a STAB Ice Shard won't be a big deal for it. This is huge for Yveltal and cannot be stressed enough, as priority is one of the biggest thorns on Kyu-B's side. Also Yveltal sounds like it will be harder to wall, as Dark + Flying + Fighting give perfect neutral coverage, not to mention that Yveltal's Dark moves are going to be insane with its good attacking stats and the boost from its ability. Compare this to Kyurem-B, whose best set mostly takes advantage of its lesser 120 SpA, and only uses its Attack for Fusion Bolt, and you can see that Yveltal is going to dish much more pain. So it's going to be more powerful and more difficult to revenge kill, qualities which, if you added them to Kyurem-B, it would start seeming pretty Uber-worthy.Those aren't especially high by ou standards
Hell, look at kyu-b, and yvel has a worse typing! Plenty of pokes have offensive stats of that calibur, with much greater speed to match.
I'm not suggesting it will lie in ou, but it wouldn't be the most farfetched thing to happen
Of 'course all of this is theorymon that is not only talking about a metagame we know nothing of, but about a Pokemon whose exact movepool and stats we don't even know yet, so treat my post more like a kind of a fun read...