i heard no one posted this yet sooooo
-brave bird/drill peck
Sp defensive skarmory is his only other viable set. With 70 base sp def he can take a special hit decent, but nothing fantastic. Moves are standard, brave bird/drill peck for stab/ so your not taunt bait, stealth rocks as he is a good rocker. Whirlwind to phaze annoying threats, while roost maintains sturdy. I probably should explain more. Evs are for a standard wall, giving him as much sp def as he can so he doesnt die at the sight of a strong special attack, allowing him to somewhat handle scarfed latios, or sets that lack hp fire, tho surf still hurts. He can handle keldeo a little better, tho hydro pump is a KO if sturdy is broken. Obviously it doesnt help against fire attacks, but its better for walling resisted moves from special sweepers such as reuniclus, tornadus, etc.
Moves are very standard. Brave bird is the attack of choice, hitting for 140 base power + the stab boost making it 210 base power, so it will hit decently hard without attack investments. Drill peck is a viable option, but its 12o base power with stab so its basically half the strength, but no recoil so its all preference. Stealth rocks is the main hazard skarmory uses, while he can use spikes, there are generally more reliable spikers like ferrothorn or deoxys defense. Whirlwind is to phaze obviously. Again roar can be used, but its the same thing, only difference is if your that guy thats like "hey i want to be different so i`ll use roar ". Finally roost is your recovery, not much else to say.
Items are obvious, leftovers increases longativity while shed shell can be used to escape from magnet pull.
Besides the obvious magnezone and heatran counters gliscor and kyurem black are 2 good skarmory answers
Gliscor can taunt skarmory and laugh as it brave birds it, doing minimal damage. One on One skarmory will loss to gliscor because of taunt, however, gliscor needs ice fang or facade.
Kyurem black negates sturdy via terravolt, thus allowing it to OHKO skarmory via fusion bolt or HP fire
252hp/4sp def/252 speed or standard wall spread
-brave bird/drill peck/whirlwind
This set would function like deoxys def, or the few custap forrys, as a suicide lead. The goal would be to set up stealth rocks, get knocked down past 25% and then have the custap berry activate and get the first move to set up spikes. As long as your opponent doesnt have a spinner/you have a spin blocker, every grounded switch in will take at least 25%.
The bread and butter of this set is the dual hazards, as it wouldnt work without them. Roost is kind of a filler, whirlwind can be used over it or you can use roost and keep skarmory to wall mid game. Finally it comes down to an attack or a phazing move. Brave bird would make it so your not taunt bait, but whirlwind lets you get rid of annoying set up sweepers. Taunt is another option to get other leads like deoxys def and terrakion, but they`re faster then skarmory so its kind of a waste
As BH said, this can set up on rotom wash. This seet can set up on alot of leads such as u turn landorus, both forms, all weather inducers except maybe abomasnow, not sure how much hp fire does, sub salac terra, scizor, deoxys def that run a bulky spread/ dont have taunt/magic bounce.
It might be best to minimize defenses so that you can help ensure that an attack will bring you into Custap range. It'd suck to be brought down to about 33%, too high for the Custap Berry but too low to restore all you health with Roost so you can use Sturdy again. Just for an example, a Skarmory with a Hasty nature and completely minimized HP and Def stats will take just enough damage from an unboosted Terrakion's Close Combat to always be brought into Custap range.
Of course, a suicide lead Skarmory is generally a bad idea, but if I were to try such a set, that's how I'd do it.
Time for something gimmicky (did not read through the first page btw, so it's possible that this set has already been repeated...)
252 Atk/252 Spe/4 HP
Believe it or not, this is the gen that finally gave Skarmory access to Iron Head. Guard Swap is meh and so is Weak Armor, but combine the two and...you still have a gimmick.
Weak Armor is actually a psyche out for your opponent, as no one would hesitate to lower Skarm's massive defenses. Once Skarm's defenses have lowered enough, then you can dish out a surprise Guard Swap and exchange your lost defenses for a brand new one. Roost can be used to heal up, after you've flinched the opponent to death, but seriously, don't go straight for Roost, go in for the kill. Iron Head gives Skarmory STAB and a nifty 30% flinch rate, allowing you enough power and chance to take out an opponent before needing to Roost. Along with Iron Head, Skarmory gets the always powerful Brave Bird to hit what Iron Head doesn't, and is complemented by Roost well.
For the love of GOD, take out any Steel trappers before using this guy, because Skarmory will be helpless against their like. This is why Shed Shell is an option, but taking care of the like of Magnezone is far safer than a one time escape. However, it's also a handy gambit against Shadow Tag Chandelure who'll also obliterate your guy.