Skarmory

Type Tier
Steel / Flying OU
Statistics
Stat
HP
65
333
Atk
80
258
Def
140
378
SpA
40
178
SpD
70
238
Spe
70
238
Name Item

Pseudo-hazer

Mint Berry / None
Moveset
~ Drill Peck
~ Whirlwind
~ Rest
~ Thief

Nothing entirely difficult here. Switch into something that can't hit it, and either Drill Peck, Whirlwind, or steal its held item. Switch out at any sign of a Special attack that could hurt it, and repeat.

Other Options

Toxic is popular on Skarmory, but not used much anymore. Sand-Attack can mess up Curse+Roar users like Kangaskhan and annoy in general, Protect is used in place of Rest and while weird, it does work. Curse could actually let it take out something if people underestimate it, and Steel Wing deals some damage Rhydon and others who are thinking it only has Drill Peck. If you decide to replace Thief with any of these moves, Leftovers is then a viable option as your item.

Opinion

One-half of the pair that started everyone banning $~BlIsSkArM~$, as chaos so eloquently put it. The only reason why a Seismic Toss Heracross makes any kind of sense, really. No physical weaknesses, a huge amount of Defense/resistances/immunities, and a decent STAB attack are pretty good.

While Skarmory is the best physical wall in the game, it isn't exactly perfect in physical sponging (though it is the closest it's going to get). Unlike Blissey, Skarmory does not have 700+ HP. It's also not resistant to Rock and Fighting attacks—coincidentally, these two types sport Pokémon with the highest Attack ratings (Rhydon, Tyranitar, Machamp, Hitmonlee come to mind), meaning it usually has trouble with these types of attackers, especially if they use Curse or Meditate. There's also the mediocre and easily exploited Special Defense, but that's assumed.

Counters

Essentially, any special attacker with an attack that Skarmory doesn't resist can beat it. Especially threatening are those with Fire or Electric-type attacks that hit it super effectively, like Zapdos, Raikou, and Jolteon. Skarmory poses little threat offensively to anything not weak to Drill Peck, so it will most likely lose to any set-up Pokemon with a slower Roar/Whirlwind.