Doubles NU Threat: Scyther

Scyther		Bug / Flying Type	70 HP / 110 Atk / 80 Def / 55 Spa / 80 Spd / 105 Spd
Abilities:	Swarm (When this Pokemon has 1/3 or less of its max HP, its Bug attacks do 1.5x damage)
		Technician (This Pokemon's attacks of 60 Base Power or less do 1.5x damage. Includes Struggle)
		Steadfast (If this Pokemon Flinches, it's Speed is booste by 1)

Even though Scyther shares the same Base Stat Total as its evolution Scizor, Scyther's bug flying typing gives it a 4x weakness to Rock type attacks (namely the ever present Rock Slide) so Scyther is here in NU. Scyther does have a powerful offensive typing in Bug Flying, and can make use of its powerful movepool along with techinican to sweep the opponents team once the Rock types are gone. Overall, while Scyther does sport heavy weaknesses, it is a prominent physical threat in Doubles NU, and can severly dent an unprepared team.

Swords Dance
Scyther @ Lum Berry / Eviolite / Life Orb
Ability: Technician
EVs: 252 Spd / 252 Atk / 4 SDef
Jolly Nature
- Swords Dance
- Bug Bite
- Aerial Ace
- Protect

Scyther's monstrous 105 base speed and 110 base attack make it an excellent Swords Dance Sweeper in Doubles NU. The item choice is up to personal preference, you can use Lum Berry to cure Scyther of burns and paralyses that will stop it sweeping, or you can choose eviolite for extra bulk. Life Orb can also be used to even further boost Scyther's damage output.The EV spread is simple to maximize Scyther's Speed and Attack, with a Jolly nature to - at worst - speed tie with other base 105s like opposing Scyther and outspeed max speed base 95 Pokemon like Stone Edge Primeape. Aerial Ace and Bug Bite are both powerful STAB moves that are boosted by Technician, with protect to avoide the omnipresent rock slide.
Pokemon that can eliminate common users of Rock Slide make excellent partners for any Scyther set. Mawile and Metang make good partners, being able to use Iron Head to smash through opposing Rock types easily. Mawile comes with the added bonus of Intimidate, while Metang is a bulkier option that is not intimidate weak itself. Scyther also appreciates a free turn to set up a Swords Dance so Scraggy and Wartorlte are also good teammates. Scraggy can use Fake Out and Wartortle can use Follow Me, and both can use STAB moves to threaten opposing Rock Types. Scyther is weak to the faster electric Types in Doubles NU so a lightning rod user like Zebstrika or Rhyhorn can also make a good teammate.

Choice Band
Scyther @ Choice Band
Ability: Technician
EVs: 252 Spd / 252 Atk / 4 SDef
Jolly Nature
- U-turn
- Bug Bite
- Aerial Ace
- Quick Attack / Brick Break

A 319 attack stat is already extremely formidable in Doubles NU and with a Choice Band boost to 478, the number of Pokemon that can survive a hit from Scyther diminishes drastically. Your opponent has 2 choices: Stay in and be KO'd, or switch out and lose momentum. U-Turn allows Scyther to scout opponents movesets, as well as gain momentum for your team, not to mention that a STAB boosted U-Turn hits hard. Bug Bite and Aerial Ace are the standard STAB moves for Scyther, but in the fourth moveslot you have the decision between Quick Attack and Brick Break. Technician boosted Quick Attack is a great option to revenge kill faster Pokemon (for example Quick Attack hits 252 HP Electrode for 36-42%) while Brick Break lets Scyther punish Rock and Steel type Switch ins. The problem with Brick Break is that while it deals significant damage to Pokemon like Kabutops, Golem, Klinklang, and Bastiodon, it fails to OHKO the standard sets from full HP, so predicting switch ins and getting prior damage is necessary for a set running Brick Break.
Scyther is absolutely crippled by being burned by ghost types like Drifblim, so running a Dark type teammate such as Zweilous or Cacturne is a good choice. If you're using Quick Attack, then you need check to the many users of Rock Slide in Doubles NU. A fighting type Pokemon like Sawk or Primeape, or a bulky Water type like Wartortle are great choices as well.

Other Options
A scarf set is possible on scyther, however there aren't many threats that Scyther gains an advantage on with a scarf, and it lacks the power to get many KOs that the Banded set does. Reversal is an interesting option that becomes extremely powerful with Focus Sash and a Swords Dance boost, but most of the time that plan won't work, especially in doubles where you can be targeted by both of your opponents Pokemon. Substitute can be used over Swords Dance, but will miss out on many KOs, and requires substantial team support. Agility can be used over Swords Dance as well, but Scyther gains little by the added speed as it already outspeeds so much of the Doubles NU tier.

Checks and Counters
Fast Electric types like Electrode, Zebtrika, and Electabuzz (if running max speed) can get the OHKO on Scyther and Outspeed. Aside from Brick Break, Scyther can do little to Rock Types like Golem and Kabutops, and Steel types like Metang and Klinklang. Bulky ghost types like Misdreavus and Drifblim destroy Scyther with Will O Wisp and take little damage from any of its attacks. Lampent may be the best one Pokemon against Scyther, resisting both of its STAB attacks and being able to OHKO with Fire Blast, Overheat, or even Heat Wave (if Lampent is Modest and Scyther isn't holding Eviolite). Scyther is also severly hurt by paralysis making any user of Thunder Wave a problem.