ChouToshio's post has been one of the few posts in this thread that have actually made a solid argument for Salamence being OU. Residual damage does hurt Salamence greatly, usually allowing it to switch in only 2-3 times. However, I think there's a hole in that argument that wasn't sufficiently addressed. Salamence isn't Flygon. It doesn't need many switch-ins to do its job. So although switching it in is a risky move, it at once seizes control of the board (continuing your chess analogy here). Now, I'm not a pro at Pokemon by any means, but I did make it to over 1400 on the ladder pre-Latias ban, so I think I'm at least decent at the game. The assumption that a lot of people are making is that the player using Salamence will just switch it in on any resisted attack and attempt to set up or grab a quick kill. This is anything but the truth. I rarely, if at all, see good players bringing Salamence in on Turn 4. Salamence's go-to switch-ins and revenge killers are easily lured out by other threats. Like you said, Scarfed Flygon isn't going to be hidden in the last slot, because it's built to scout and revenge kill throughout the game. Salamence isn't going to be brought out while that's around (unless you anticipate it switching in and fire off a Draco Meteor). When Salamence does come out, it has precisely the effect of a Queen in chess. Suddenly, it becomes the center of attention. Nothing else in OU has that kind of presence. I don't think it's exactly balanced to have a Pokemon like that in the metagame.
I would also like to add that the game doesn't end when you kill Salamence. A lot of posters have repeated again and again that even if you switch in a bulky Pokemon predicting MixMence and let it get off a DD, that you can revenge kill it by forcing it to Outrage. Ice Shard users, Scizor, Scarfed Flygon something else bulky enough to take a +1 Outrage and 1hko with Stone Edge or Ice Beam. I'd like to point out that every almost single one of these commonly used revenge killers gives another Pokemon a free turn. So you switched in Weavile and got rid of Salamence with Ice Shard. Good for you. Now Gyarados has a free turn to DD, or Metagross has a free turn to Agility, or you also lost you revenge killer in addition to what you lost to Salamence. How many Pokemon carry a Choice Scarf just to revenge Salamence? How many of those Pokemon are going to be locked into a resisted move after they revenge it?
But by the same token, Salamence having that kind of presence doesn't make that presence broken by default. As Chou pointed out, Mence often has a single opportunity to sweep, and it failing to do so means that the significant effort of your team to meet those conditions have all been wasted (I'm referring to the Dancer here, I'll get MixMence later).
And if Salamence is indeed the deadliest threat in OU as you imply, revenging it is ALWAYS the best course of action - who cares if Gyara sets up DD or Meta uses Agility, as long as Salamence (the most dangerous one) has been taken down.
There are several notable OU pokemon capable of taking a +1 attack and retaliating. Calcs assume 364 Attack at +1 with a LO:
Outrage vs. 252 / 252 Relaxed Swampert: (73.76% - 87.13%)
Outrage vs. 252 / 252 Bold Suicune: (63.12% - 74.26%)
Outrage vs. 252 / 228 Calm Cresselia: (62.16% - 73.20%)
Outrage vs. 252 / 168 Impish Hippowdon: (63.10% - 74.52%)
Outrage vs. 252 / 220 Bold Celebi: (70.54% - 83.17%)
Outrage vs. 252 / 252 Impish Donphan: (64.06% - 75.26%)
+0 Outrage vs. 252 / 252 Impish Gyara: (55.08% - 64.97%)
Outrage vs. 252 / 220 Bold Shaymin: (70.54% - 83.17%)
Outrage vs. 252 / 252 Bold Slowbro: (66.50% - 78.43%)
Fire Blast vs. 212 / 44 Impish Torterra: (70.57% - 83.07%)
Earthquake vs. 252 / 0 Careful Regirock: (64.84% - 76.37%)
I excluded the steels for obvious reasons. All of these pokemon do have their merits, however:
-
Swampert: We all know what it does. It is often seen in the lead position however, and lack of recovery hurts it. Still a nice check though.
-
Suicune: Max / Max Suicune is almost always seen running a Cro set, but nobody ever thinks to just forgo Calm Mind and give it Ice Beam. If it comes in on Draco Meteor, you survive with about a third of your health (which you can Rest later). The thing is, now you know that Mence has to Outrage to secure the kill. Free switch to a steel.
-
Cresselia: Some people say it is useless, but in all honestly I disagree. It can spread paralysis around your enemy's team as well as provide screen support, which is never useless. Her equal defenses allow her to take on both MixMence and DDMence, either paralyzing it or going for the kill with Ice Beam. Scizor and Tyranitar are around? You know they're coming out to harass her, so just Thunder Wave / double switch to an advantage.
-
Hippowdon: The only drawback is that it sets up Sand, though that further weakens Mence so it evens out. It can set up rocks, has instant recovery, and its awesome defense helps it check other top threats such as Tyranitar and Metagross.
-
Celebi: Everyone has all but forgotten about the onion in its defensive form, which is annoying to face and equally as difficult to take down. Recover keeps her at full health throughout the match, and HP Ice disposes of Mence when she needs it. Yeah it takes alot of damage, but it is pretty speedy and has Lefties and Recover to restore its health when it gets the chance.
-
Donphan: Rarely shows its face around OU anymore, but it still has its uses. If it switches in on a DD, it gets to Ice Shard Mence before taking a hit, then Ice Shard again for the kill. And if you are running Donphan, odds are it is spinning, which helps out with removing rocks.
-
Gyarados: It's a stretch, but it can switch in and Roar Mence out in a pinch if it has to. Temporary solution at best, but Mence will come back in with about 28% later on (1 round of LO, 2 hits of Stealth rock, and 2 hits of sand), effectively crippling it.
-
Shaymin: An alternative to Celebi, if you dislike Pursuit ruining your fun. Natural Rest helps it with recovery.
-
Slowbro: Has been all but forgotten. Reliable recovery, great defenses, and Ice Beam put DDMence in its place. It can also deal with Gyarados, Metagross, Heatran, and other threats.
-
Torterra: Rarely seen, but the defensive set can take a hit and strike back with Stone Edge. Aside from Mence, it can cover threats like HP Ice-less Jolteon, Tyranitar, Metagross, Jirachi, and more.
-
Regirock: I'm really unsure as to why this isn't used more. It's uninvested defense is still sky-high, and it has access to great support moves like Thunder Wave and Stealth Rock. It benefits from the omnipresent sand, and can check certain threats (Tyranitar, Heatran, Jolteon, Flygon).
I realize this list contains some unorthodox pokemon but why should your options be restricted to those in OU? Nearly all of these checks can also take a Draco Meteor from Mixmence (the best options to do so being those with Recovery, obviously). Additionally, they essentially force Salamence to use Outrage to secure the kill, which is when you go to the steel. Dealing with Mence is really a matter of forcing it to choose between Outraging or dying, which gives you some leeway when it comes to deciding your next switch-in.
EDIT: Aside from checking Mence and playing around it, it is very difficult for DDMence to sweep without considerable support. Magnezone is almost mandatory for Scizor and ScarfJirachi, as well as a wallbreaker to soften the things that can withstand an attack here and there. Not to mention that it still often ends up banking all of its success on winning a speed tie against Jirachi, Flygon, and others. The support required is too much for the DD set to be considered Uber, IMO - if anything, it is closer to fulfilling the support characteristic with the Mixed sets.