SpecsMence isn't outclassed by Latios, but it's strictly worst for the most part. It's slower and has a SR weakness, which is a serious drawback on a choiced user that's main STAB forcing it out. That U-turn resistance is absolutely worthless since chances are your opponent is going to bring in something that can force Salamence out (not a good thing with a SR weakness) and Intimidate is limited on Specsmence, since you don't want to switch it into just anything (you're limited to just weak special attackers like ninetales and Breloom). The Pursuit neutrality is nothing to brag about; CB Tyranitar is guaranteed to kill you on the way out if SR is out, and Scizor is doing heavy damage.
The reason why we like Specs Latios but hate Specsmence is because Latios still gets rely on his incredible speed stat in addition to its overkill Special Attack to kick ass. Its incredible easy to use as well... like, much, much, much easier to use than Specs Salamence. It's very easy to do excessive damage to most teams by just spamming Specs Draco Meteor alone, and Latios hits more relevant targets because its faster. Specs Latios doesn't need to gamble when Surf is doing obscene damage to most of its checks (Surf is a guaranteed 2HKO on CBtar and Scizor switching in with SR) and that's without rain(Latios isn't even hard countered by Jirachi if Rain is up!!). Specsmence doesn't have any of Latios's luxuries. It doesn't have that amazing speed stat, and it always has to contend with that SR weakness, which guarantees it gets 4 switch ins at most. Salamence is even riskier to use than Latios, since it needs to hits checks with the right coverages or else it just invites a ton of Pokemon to switch in. Even if you do land a solid hit on something like Ferrothorn, there's always something thats going to come in and force you out, and *again* its SR weakness punishes you for that.
When you factor Draco Meteor tends to force SpecsMence out, and that most of the best Pokemon in the tier naturally outspeed it, you realize SpecsMence is getting force out a lot, so it doesn't get to stick around as long as Latios and it can't be used to check some of the best Pokemon in the game like Latios can (Terrakion, Landorus, etc). The worst part about Salamence is that Hydreigon basically outclasses it. There is nothing that Specs Salamence does that Hydreigon doesn't do as well/better. The extra speed it has over Hydreigon is inconsequential, and Specs Mence isn't going to be putting its ability to good use. It's only really advantage over Hydreigon is that it can't be revenge killed by Breloom, but I don't think we should give Specs Salamence a set on that reason alone.
my first set ;D
