Altaria @ Altarianite
Cloud Nine -> Pixillate
EVs: 252 HP / 4 Atk / 252 Def
Impish Nature
- Facade / Return (possibly Body Slam)
- Dragon Dance
- Cotton Guard
- Roost
Been running this set recently. Because many of Altaria's common checks I've run into are physical rather than special, it's quite easy to wind up in a situation where Altaria comes in with it's only opposing checks being the likes of Scizor, Mamoswine, Ferrothorn, M-Metagross, Bisharp, M-Beedrill, etc. The general idea with this set is to come in on something it can easily force out, set up a cotton guard while they expect a DD, going for that +3 Def, then another as they try to break Altaria with their strongest super effective STAB physical attacks. At +6, Roost if you need to and stack DDs with impunity while they switch to something to status you (lol wisp) or simply forfeit if you've played it well.
Rotom-W is another common poke I've run into, in addition to sometimes M-CroBro (watch out for Ice Beam), which is why I prefer Facade over Return when running a bulky set intended to set up a bit more before sweeping -- with the extra turns you'll be setting up it just finds itself getting burned so frequently, which would otherwise shut it down if running Return). Getting Toxic'd is obviously less satisfactory, but by the time opponents switch in a toxic user I've usually had enough time to set up enough that Altaria can take 2-3 pokemon down in a last ditch effort. I think a lot of people have an aversion to facade because they can't get over 70 BP, but remember with Pixilate's x1.3 it's 91 BP when healthy, which is 1 point higher than MOST physical fairy-type's
best attack (Play Rough) with
better accuracy. It's a matter of risk/reward over Return, but I find that the risk isn't much, while the reward is massive (182 BP before STAB, bypassing common burn).
I'm admittedly not good/lazy with EVs, I'm sure Defense can be scaled down to a certain benchmark (as after a cotton guard or two it becomes overkill) and the rest can be pumped into Atk/Spe (or even SpD) based on your needs. Personally, I've found that it doesn't need SpD as much, as Dragon/Fairy already gives it useful resistances to many common special attacking types (fire/water/grass/electric, plus dragon immunity which is pretty much 50/50 in OU). Going physically defensive also allows it to counter rather than check lati@s, as it resists or is immune to Draco Meteor, Thunderbolt and HP Fire, and the only unresisted attack they run is psychic- STAB, which is usually Psyshock to avoid getting walled by the blobs, which just so happens to force them to hit Altaria's bulkier side.
Running Cotton Guard also allows it to beat Ferrothorn and Talonflame one on one, which can check or outright counter other sets. If possible, Alt can boost up it's defense before mega evolving for an easy time against Ferro (or other steels), but even if it's already Mega Evolved, with two Cotton Guards Ferro can't even touch a +6 speed Altaria with Gyro Ball. Same with Talonflame, you'll get Defense up to +6 before it gets it's attack that high, then when both are at +6 use a combination of DD/Roost to beat it. Or if it WoWs you'll win the matchup much easier. SD Mega Scizor still beats this version of Alt one on one, quite handily if it comes in after you've mega evolved.
The pokes that check this are obviously powerful special attackers with super effective attacks - Greninja for the time being, Gengar if running Sludge Wave, Heatran if running Flash Cannon, MeGarde, and Thundurus/Lando-I off the top of my head for common OU pokemon, so it's best to pair it with something that can handle these.
Just a couple replays, the rankings are low since I had just begun playing in the suspect test latter like, the day before it went down, and just started laddering in the new OU:
http://replay.pokemonshowdown.com/ou-200004367 early CG set ups rendered it unbreakable while DD'd and swept the opponent, only 2-0 before the forfeit, but it obviously would have been a 6-0.
http://replay.pokemonshowdown.com/oususpecttest-199830541 Same as above, essentially.
http://replay.pokemonshowdown.com/oususpecttest-199766905 This one is a little dodgy as I don't know why anyone would use regular Aggron in OU play, but either way it's STAB Heavy Slam (100 BP?) was unable to break CG M-Alt as she stalled it out while setting up a few DDs, forcing yet another forfeit.
http://replay.pokemonshowdown.com/oususpecttest-199612112 ^ Same as above, this time with a Delphox... Still, with a single turn of setup non-LO Mamo's 5x Ice Shard only did about 30-35%.