Altaria @ Altarianite
Ability: Natural Cure to Pixilate
Nature: Naughty (+Sp Atk, -Sp Def).
EVs: 252 Sp Atk, 252 Spd, 4 Atk.
-Dragon Pulse: Coverage/STAB
-Fly/Sky Attack/Roost: Fly for convenience in your party, Sky Attack for STAB and the chance of flinching, Roost so you can heal.
-Moonblast: Coverage/Lowering Special Attack against your opponent down 1 stage.
-Cotton Guard/Earthquake: Defence against Steel, Poison, Fairy, and Ice types, Earthquake for more type coverage.
This set is meant to give your Altaria a good movepool to defend against a bunch of types. For your flying type move, you have three options. Fly for convenience, Sky Attack for flinching and stab, and Roost, to heal. For your fourth move, you can choose a defensive move, Cotton Guard, to up your defence drastically. Or you can have an attack to give your Altaria a wider movepool. Whatever you feel is best whether it's an attack or a defence. I hoped this helped, and gave you an idea for a good set for your Altaria. Thanks for reading.