Running it on offense for phasing or spikes is like running Blissey on offense because it clerics for you
First off, that is a terrible example because there are far better clerics for offensive teams than Blissey (think Diancie or Xerneas). Since Skarmory can actually do something for Offensive teams, the comparison to Blissey is something I find to be very distraught and I just don't understand the point you were trying to make here.
It kills momentum and there's things better than it that you can use on an offensive team. Slapping random defensive Pokemon on offense is bad because, while they wall a few things, they're inevitably bait for others. It's putting inherent momentum killers on teams who are very reliant on keeping momentum to check threats; while Skarmory can wall Mega Kangaskhan for you, what happens when the opponent brings out, say, Yveltal and you have to scramble to find a switch-in
Setting Spikes on things you wall is not losing momentum. That's offensive pressure; do not confuse the two. You also assume in the scenario you created that my Skarmory team lacks a Yveltal check. I wouldn't be scrambling for a switch-in after I set Spikes on Khan switching out to Yveltal, I would appropriately be switching into, say; my ScarfXern, forcing out your Yveltal and racking Spikes damage. Unless you meant Khan baited Skarmory and you doubled to Yveltal, even so; that would only mean I was outplayed.
At any rate, it's not a surefire check to some of the things you mentioned anyway. You already mentioned that it loses to Fire Blast Ekiller, and it loses to the viable Fire Blast Salamence, but it also gets mauled by Thunder from Latios/Latias and V-Create from SD or DD Rayquaza, both of which are totally viable. It walls Lugia which certainly isn't a distinct defensive niche for it; legitimately any Defensive steel type (and some Offensive ones) can do this, and Mega Kangaskhan is pretty uncommon in a tier where Mega Salamence and Mega Gengar are the preferred megas of choice for most teams.
SD Ray should not be using V-Create, it literally only hits Skarmory which is very targeted - Ray could be hitting much more with Earthquake or Dragon Ascent. Unless Skarmory became the premier check to SD Ray, V-create would be mentionable; but because Ray isn't metagaming around it anytime soon and is instead tripping over its tail about Ghostceus, Rockceus, and Xerneas; your argument here is entirely invalid. The DD set is in a very similar predicament. I feel that Overheat/Fire Blast is the best option in the set's fourth moveslot, but priority needs to be on just about every team, and it pains me that I see ExtremeSpeed on just about every DD Rayquaza on the ladder. But again, in my OP I specifically said
"It's easy to meta-game around, but for now it needs to be at least B+." The "
for now" part suits the huge '
Preliminary' in the title of the thread. Skarmory is a check to DD/SD Ray now, and unless it changes for the worst Skarmory can be dropped from what I am nominating it to.
I find it silly that you said 'Thunder' and 'Latias/Latios' in the same sentence. There is no room for Thunder in the moveslots of either of those two mons. If you aren't using Defog/Roost on Lati@s then you just aren't using them properly. You need both STABs for obvious reasons, and Roost is really necessary to check POgre better or to keep setting up CMs if that is the set they're using. I feel Latios can
possibly run Thunder, but if someone is using Latios it is probably for the CM+Draco Meteor set consisting of CM/Draco/Psyshock/Roost, which I specifically excluded from the things that Skarmory can wall.
Also, what you said about Skarm walling Lugia only strenghens my argument. Lugia is really easy to bait with strong physical set-up sweepers (which should be paired with Skarmory), and what is quite literally a free opportunity for Skarmory to set Spikes or spam Toxic is amazing for offensive teams.
I only mentioned Khan because it's a part of the tier and is still quite viable. I realize that the S Rank megas fulfill greater niches, but since MKhan is Uber I felt it justified to include it into what Skarmory can wall.
Oh, and the point about it being Taunt bait is a little confusing as Mewtwo, Yveltal, and Gengar beat it anyway (not sure what you're trying to say?) Regardless, I feel that Skarmory has more or less as much of a defensive niche as Pokemon like Hippowdon and Sableye based on things you already mentioned in your post and I'd support a rise to B- Rank.
Yeah, I probably sounded confusing in that part of my post. But what I was trying to point out is common Taunt users have declined in usage for now, which is great for a Taunt-prone pokemon such as Skarmory. Mewtwo just doesn't seem to fit on todays teams and its Megas have become a lot less usable because how great Mence/Gar/Diancie are. Gar is in the same predicament since its usage has seemed to decline due Mega competition with Mence and Diancie. I don't know why I mentioned Yveltal in my OP; it beats Skarmory regardless of Taunt. Sorry for the confusion.
Hippowdon and Sableye... just no. Hippowdon is outclassed as an SR setter by other mons in the tier and is a sad check to Ekiller - it will lose half of its health to +2 Espeed and has very poor resistances to remedy its awful special bulk, and thus cannot handle common special-attacking types of the tier. Skarmory does exactly what it does with a better typing and resistances, with literally the same features of reliable recovery and big defense. Skarmory will lose to the rare Fire Blast Ekiller, but I consider that to be severe counterteaming; something quite unavoidable when your check to a mon is the one being over-prepared for by your opponent.
Sableye is just eww. He's fairy bait and is hard-walled by MDiancie, at least Skarmory can run Iron Head>Toxic to beat it. Taking into consideration how burn-stall is impossible to do with PDon trampling around, I'm quite surprised you had the dignity to even mention this mon, especially when it has a much more superior Mega form; but even MSableye is caught up in the Mega slot competition.
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Tl;dr Skarmory has a great niche of checking several of the tier's A-S rank mons, and deserves
B or B+ Ranking.
Regarding Dugtrio, I'm sure it could be a cute gimmick but I certainly wouldn't lead Primal Groudon if I saw that my opponent has Dugtrio, not to mention that you'll have to double heavily with a massively frail Pokemon for it to handle Primal Groudon as there's no way in hell it'd get a free switch-in and it can't beat it if it switches in on an attack because of the calc you provided. I'm not even sure what it does outside of beating Primal Groudon some of the time. Maybe it traps other OU Pokemon like Tentacruel or Tyranitar when given a free switch but it's not like those are common anyway. I'd be totally fine with leaving it unranked oo
I didn't think anyone would take that part of my post seriously lol. You implied that it would take a considerable amount of skill to use it by saying it would take a huge amount of double switching in order to trap PDon with it; but that basically extends out to what determines a C Rank mon, so imo it it should be in the OP somewhere.
C Rank at least.
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Sorry bae I love you but I had to shoot down your points :[