As its NFE status implies, Dragonair should not be expected to strike fear into its opponent's hearts just by appearing in Team Preview (unlike its evolution), mostly because its only practical role in the RU metagame is one thing, and one thing only: Dragon Dance sweeping. Fortunately, despite its admittedly average stats, Dragonair can distinguish itself from other attackers with its exceptional Dragon typing. As a special note, the generation shift granted Dragonair a gift in Eviolite, which gives it a golden opportunity to be a viable defensive sweeper in RU. Although its options are pretty limited outside of Dragon Dance, being able to boost both its Attack and Speed at once is always a valuable asset in an environment that lacks solid Dragon Dance users, or Dragon-types, for that matter.
It's not very often one sees a bulky boosting sweeper in the predominantly offensive RU metagame. Dragonair, however, can fulfill this role successfully thanks to its typing which gives it a few resistances and only two weaknesses, access to Dragon Dance and Shed Skin, and boosted defenses via the Eviolite. The key to using Dragonair, however, is to be conservative; only attempt a sweep when you have eliminated any opposing powerhouses, as Dragonair's bulk isn't exactly game-breaking. The most efficient way to start the sweep is to switch Dragonair into something that can't hurt it significantly, which applies mostly to Grass-, Electric-, Fire-, and Water-types, as well as defensive Pokemon in general, such as Slowking and Tangrowth.
Dragonair's primary focus is attaining multiple Dragon Dance boosts while the opponent attempts to respond (likely by using status or switching in a check). Status is nothing to worry about as far as Shed Skin is concerned, so feel free to set up on any predicted status except sleep. If Dragonair sustains a major amount of damage, simply use Rest to recover. Do not be over-reliant on Rest, however, as Shed Skin only has a 30% activation rate. Once Dragonair has secured a number of boosts, simply lash out with Outrage. Though somewhat unreliable, Outrage can put huge dents in anything that is not extremely bulky, or a Steel-type.
In addition to being one of the few usable defensive sweepers in RU, Dragonair is one of the tier's only offensive Dragon Dance sweepers, with its only notable competition being Feraligatr. After a single boost in conjunction with Life Orb, Dragonair has the potential to tear teams apart. Unlike its fellow Dragon Dance user, Dragonair boasts an advantage in its Dragon typing, which is useful both offensively and defensively. Dragonair also has a powerful STAB attack in Outrage, which provides raw power and coverage against everything but Steel-types, which are covered by Dragonair's chosen Water-type move. Dragonair can choose either Waterfall or Aqua Tail; again, a power versus accuracy dilemma. This alone makes Dragonair a hard attacker to beat, seeing as it can break through threats with Outrage's sheer power and exceptional coverage.
On top of this, Dragonair has been graced with the rare ExtremeSpeed, which allows Dragonair to beat revenge killers and other priority users, such as Hitmonchan and Absol. As a small bonus, Shed Skin gives Dragonair a "second chance" to function if status happens to get in the way, though relying on it is highly inadvisable due to Dragonair's decreased bulk.Team Options & Additional Comments >>>
Dragonair is the antithesis of its more versatile and powerful evolution; Dragonair unfortunately lacks the options, let alone certain stats, to do what Dragonite would do to make an impact. In short, the few options Dragonair does have are limited by unimpressive stats. For instance, Dragonair can make use of some useful special attacks such as Dragon Pulse, Draco Meteor, and basic coverage moves including Ice Beam, Flamethrower, Thunderbolt, and Surf. However, its low Special Attack, even when invested, hinders the effectiveness of these moves quite a bit. The only other notable physical attacks are Dragon Rush and Aqua Jet, but both are hard to fit on either Dragon Dance set due to redundancy (and accuracy in Dragon Rush's case).
Dragonair is more affluent in support moves, but more often than not, its only decent bulk and lack of reliable recovery will let it down in more defensive roles. Dragonair's hidden ability, Marvel Scale, isn't of much use because of the limitations that come with it, such as the lack of Sleep Talk (so any chance of using the RestTalk combination is out of the question). As for support moves, Haze, Thunder Wave, and Safeguard are certainly useful options. Light Screen can prove useful on the defensive Dragon Dance set, granting Dragonair easier setup against special attacks while allowing it to invest more in physical Defense.
Checks and Counters
When facing Dragonair, the best thing to do is strike it down with force. With or without Eviolite, Dragonair is only decently bulky, and much frailer on the physical side. For instance, Entei has a chance to 2HKO +1 252/0 Dragonair with Flare Blitz, factoring in Life Orb and Stealth Rock damage. If the prospect of a healthy boosted Dragonair is frightening, certain bulky Pokemon such as Ferroseed, Tangrowth, and Hariyama will have little trouble taking some boosted attacks (in moderation). Keep in mind, however, that attempting to stop Dragonair with status may be a wasted effort because of Shed Skin. Quagsire in particular is one of the best counters to Dragonair, as it will be Unaware of Dragonair's boosts, and can wear the dragon down with consecutive Earthquakes. In a worst-case scenario, priority users and Choice Scarf Pokemon with a base Speed of at least 55 can still revenge kill Dragonair successfully, the most notable being Medicham and Primeape.