Cotton Guardian
Altaria @ Leftovers
Trait: Natural Cure
EVs: 248 HP / 204 SDef / 56 Spd
Careful Nature
-
Cotton Guard
- Dragon Dance
- Dragon Claw
- Roost
Leftovers is standard for recovery, and Natural Cure will let you heal status on the switch if you want Altaria to come back strong later. EVs are to maximize special defense while still hitting 210 speed to outrun 252 speed base 55 'mons like Relicanth, Exeggutor, Ampharos, and some wacky Golurk. It will also beat minimally invested base 85s like defensive Articuno.
-Cotton Guard is the crux of the set. After a single boost, Altaria's defense rockets up to 540. One more and it reaches a sky-high 864. With defenses like these, it's easy to start using Dragon Dance.
-Dragon Dance patches up Altaria's terrible uninvested base 70 attack and quickly lets Altaria outrun many unscarfed Pokemon. (Two boosts for most scarfers.)
-Dragon Claw is just about the best mono-attacking move available, but Outrage can be used if you don't care about being trapped.
-Roost is for instant recovery, and can make Altaria a real bastard to take down. It removes weaknesses to rock, halves the weakness to ice, and lets Altaria resist electric. (Though you'll need a DD or two to get it off first.)
It's incredibly easy to switch in and start using Cotton Guard against some Pokemon, particularly grass types. (The ones that don't have ice beam at the ready.) With Natural Cure, Altaria can come back again after being crippled. This set does face some issues with phazing if it isn't strong enough to break the phazer before boosting. Even at +6 defense, physical ice moves are still going to hurt a lot. I've used this set for a while, and Altaria can become an immediate threat three or four times a match, easily.