Doubles NU Threat: Altaria

Altaria		Dragon/Flying Type	75 HP / 70 Atk / 90 Def / 70 Sp.Atk / 105 Sp.Def / 80 Spd

Altaria is a strong threat in Doubles NU, holding the titles of both the strongest Draco Meteor (tied with Dragonair) and the natrually bulkiest Dragon. Add that to the fact that there are not many fairies in NU, and that Altaria has a wide movepool for both support and offence, and you can see why Altaria is a strong choice for a team.
Altaria is not without its faults however, sporting a 4x weakness ice attacks means that Altaria is not only forced out by faster ice pokemon like sneasel and jynx, but must also be wary of slower pokemon carrying ice shard, and water types carrying ice attacks. Altaria is also weak to the ever present Rock Slide, and is vulnerable to the many faster electric Pokemon in NU.
That being said however, Altaria has access to a variety of moves and abilities that allow it perform well in Doubles NU, so lets take a look.

Altaria @ Life Orb
Ability: Natural Cure
EVs: 252 HP / 252 SAtk / 4 SDef
Modest Nature
- Draco Meteor
- Fire Blast
- Tailwind / Rest
- Protect

This Life Orb set lets Altaria make use of both its powerful special movepool and its support moves. Draco Meteor is used as a primary STAB to hit everything hard, and OHKO opposing Dragons types, while Fire Blast is used as a coverage move to hit Steel types. Altaria does have access to the spread move Heat Wave, however because of Heat Wave's lesser base power, and the damage drop from spread moves, Heat Wave misses out on OHKOing 252 HP Klinklang and 2HKOing 252 HP Metang. Life Orb and Modest are also required to achieve these hits.
Because we have Tailwind as the third move, we have invested maximum HP to increase the chances of setting up Tailwind, however Rest can be used to Heal Altaria, who is cured from sleep upon switching out thanks to Natural Cure. Cloud Nine can be used to beat Parasect and Ferroseed that like to use rain to cover their fire weakness, or to slow down any speedy weather sweeper. If you choose to run Cloud Nine, make sure that you're not using rest!
Steel Types make excellent partners for this set, resisting Altaria's weaknesses to Fairy, Dragon, Ice, and Rock and being able to hit back on 3 of those types for super effective damage. Klinklang and Metang make great partners, Metang also being able to beat Fighting types like Sawk and Throh that like to carry Ice Punch, however Metang must be wary of sneasel. Fast and Powerful fighting types like Sawk and Primeape are also good partners to take on Rock Types and Piloswine, who can use EQ to beat Steel types that Protect Altaria.
Altaria can use Tailwind to support Swords Dance users like Samurott and Scyther.

Bulky Dragon Dance
Altaria @ Sitrus Berry
Ability: Natural Cure
EVs: 104 HP / 252 Def / 152 Spd
Bold Nature
- Dragon Dance
- Dragon Claw
- Earthquake
- Protect

Although Altaria is primarily outclassed as a Dragon Dance user by the more physically powerful Dragonair (who also has access to Shed Skin), Altaria is still a strong user thanks to the phenomenal coverage given by Earthquake and Dragon Claw, and the freedom to use an item where Dragonair is limited to eviolite. The EV spread allows Allows Altaria to outspeed Fraxure before a boost, and outspeed adamant Floatzel after a boost. Dragon Claw is the primary STAB move, with Earthquake to give great coverage against Steels. Sitrus Berry is used as the item to give Altaria even more bulk, with Natural Cure to allow Altaria to attempt another set-up sweep after switching out.
This set does not actually well with Ragepowder and Follow Me users in the Doubles NU tier because all of the available users except for Butterfree and togetic are grounded and thus will take damage from friendly Earthquake. Butterfree is likely your best bet because it can also put opponents to sleep, although it is weak to ice moves that will target Altaria and will not be able to draw them away and survive the majority of the time.
Instead, using Pokemon with access to intimidate like Masquerain is a solid option to weaken the opponents attacks on Altaria, while still leaving Altaria free to fire off Earthquake into opposing Steel types.
Altaria can run a more offensive EV spread with this set, however it is outclassed as a hyper offensive Dragon Dance user by Fraxure.

Other Options
A mixed attacking set appears viable, however Altaria's Offensive stats just aren't high enough to be able to use without full investment. Altaria was given Moonblast and Dazzling Gleam in Generation 6, however Draco Meteor does more damage neutrally than a 2x super effective Draco Meteor, so Moonblast is only better against Scraggy and Zweilous, and Zweilous is weak to Draco Meteor anyway.

Checks & Counters
Steel types are very strong against the Life Orb set, being able to switch in for free after Altaria is at -2 Sp.Atk from using a Draco Meteor. Fast ice types like Jynx and Sneasel beat Altaria before Dragon Dance boosts with Ice Beam, while all Ice Shard users give Altaria problems. Bulky Rock types like Golem also give Altaria trouble, Golem can survive a Draco Meteor and KO back with Stone Edge or a 5 hit Rock Blast. Electric types and Water types with ice attacks give Altaria trouble, particularly Floatzel who outspeeds Altaria and can hit hard with Ice Fang. The many faster electric pokemon can do serious damage with their STAB electric attacks, and many carry Hidden power Ice, beating Altaria. Finally, Altaria is weak to Fairy types, particulalry Wigglytuff who can OHKO Altaria with Ice Beam. Mawile also threatens Altaria with play Rough, but must be warry of Earthquake or Fire Blast.