All of the Pokemon listed sans Scyther are heavily impacted by SR (because obviously Scyther was never gonna be OU regardless). Their roles and niches ARE being cut short due to that massive weakness.
Perhaps I didn't make the point of that post clear; but those were just examples of Pokemon that aren't completely useless due to a 4x weakness to SR--much better examples than lolmega.
Moltres on paper sounds ok, but it has too many conflicting things going on... He's an awkward Pokemon for OU, for that niche. It's outclassed as a generic special sweeper or Spec user, so then it's further narrowed down and constricted in usefulness
I don't wanna sound like a wannabe OU player--but have you even used it? Digging for concrete in the sky will do nothing but keep your head suspended above the clouds. I've been using Moltres on my main team since the production of its first Gen V OU analysis; other creditable players have used it as well and don't find it to be 'outclassed as a sweeper or Spec user'. How you can make such audacious statements is far beyond my understanding. Now, onto ripping apart this portion of your post:
You want 100% Hurricane at the cost of weakening Fire Blast, 100% Thunder from other Rain comps, having a Pokemon that's basically worthless defensively sans vs Sun Teams, etc.
Your ignorance knows no limits, does it? First of all, Fire Blast, even with its power halved, hits its intended targets (most Steel-types) for heavy damage. Jirachi is literally the only target that Fire Blast doesn't outright KO; and even then, LO Hurricane + Fire Blast usually secures the KO on SDef variants. Also... huh? Since when is being able to casually switch into Celebi, Lucario, Lando-I (again, I have to stress this one because it's one of OU's top threats), basically every Steel-type, Ninetales, Heatran, Breloom, Gliscor (though, it's not as relevant in OU as Lando-T), a fair amount of Jellicent, Mamoswine (haven't seen Stone Edge in months), basically all of standard hail, and many others worthless? I don't have a clue which metagame you're playing, but in BW2 OU, that's pretty vital.
Oh, and I have my doubts that 100% accurate Thunders mean much when you're OHKOing every-****ing-thing in your path. Granted, it forces Moltres to tiptoe around like, Thund-T, Scarftom-W and SDef Jirachi, but a bit of patience will result in all three Pokemon getting scrapped.
Agility Set won't have the power you want/need, Spec sets are slow and poop easy to revenge, it's not good. Without rain, basically kiss Hurricane goodbye.
Oh, I'm sorry! Base 125 Special Attack apparently isn't powerful enough for OU. I guess that Tornadus-I is super bad in OU after all and deserves nothing higher than UU status. Man, everyone must've been (and still are) following some wack ass standards if they're resorting to using something with base 125 Special Attack. C'mon, I know you're smarter than this.
I also question the idea of Articuno in Ubers, because how would it shine in that role better than another choice? I don't understand Hurricane, in Ubers, from an Articuno... being that amazing lol. Ice STAB is great, but it hits like a weak puny *****. Articuno doesn't even muster 100 base SA, that's not impressive enough to scare off enough threats. What scenarios are popping up, that he's proving to be useful? If a Specs Dragon is out, you either soak the hit switching Articuno in or Articuno is coming in after the faint. The first scenario can get real ugly if SR is around, the second isn't special because plenty of Pokemon can force the switch from Latios/etc Pokemon that just Draco'd. If the Pokemon is neither weak to Ice or Hurricane, you probably won't have the offensive muster to threaten it. If it's a CM user, maybe you can Toxic it, but yeah I'm just not seeing it. It sounds like a huge liability and more like a limited option against the people that don't play Kyogre as well as they could/similar pokes. Special Sponge, but gonna do poorly against Electric and Fire. Not to mention that awful typing is **** for dealing with Priority.
Have you used Salamence + Rayquaza in Gen IV? It's pretty much the same concept. Take something noticeably weaker than a powerful threat in Ubers and use it to weaken said threat's checks and counters juuuuuuuuust enough for them to finish off later. Articuno pairs well with something along the lines of Kyu-W--something that greatly appreciates particular defensive threats softened up a bit before wreaking havoc. It's not something that I would consider practical, but hey, Speed Boost Yanmega in BW2 UU is no better.
Yanmega went downhill with Team Preview, same with Ninjask, because knowing beforehand about Speed Boost Pokemon is a huge boon and can easily allow you to stop or plan for their setup. The only hard flaw that he had in DP (besides SR) was that he just didn't hit hard enough. He had too many counters though, and Team Preview further ruined him (that and SR being used on more than dedicated leads was a bad shift for him)
DPP OU right before the introduction of BW (and by extent team preview) didn't have anymore trouble with Yanmega than early BW1 did. Power wasn't its problem back then; Yanmega hit just about all of OU's top players for either super-effective or heavy damage. Yanmega struggled with separating itself from its competition, Starmie in particular due to comparable coverage on the metagame and 'high enough' Speed stat. To keep things short, if you prepared your OU team for most standard threats, then you'd have Yanmega more than handled. Speed Boost or not, if my team can handle something as simple as FWG core, then it should be able to munch on Yanmega.
also, Ninjask is rarely used outside of the lead position, and even then, the presence of something overall pathetic defensively desperate to set up will be made obvious pretty early in the game. "My opponent lead off with Aerodactyl? They obviously don't want rocks up, so I should keep my revenge killers and / or phazers healthy."
Using Specs took away the Protect option for securing a speed boost, and severely limited you in coverage because you can't afford to be stuck on 1 move and then watch Heatran switch in for free. With a bit more power behind him/better STABS, he would have been nasty in DP.
Better STABs? He Bug Buzz / Air Slash covers pretty much the entire tier lol. Also, Specs + Speed Boost is very ass and I genuinely have no idea how it came into this conversation. But yeah, I definitely agree that if Yanmega had at least base 130 Special Attack, it would rock DPP OU.