Analysis

 Gyarados is by and for the most threatening setup sweeper in the December metagame, and one of the most interesting to use in 35 pokes as a whole. Why is Gyarados so threatening in this format in particular, where water is effectively its only reliable STAB? Well that's a discussion for another day 

↓ [Really quick-the flying type helps ATON, and the fact that it doesn't need to run a damage-posting item allows it to make up for any potential shortcomings]

 There is only one grass-type and two electric-types; Chesnaught, Pincurchin & Eelektross. Morpeko and Eldegoss are more niche picks that can be an issue for Gyarados if unprepared, but access to temperflare and bounce can unexpectedly flip the matchup on its head. Morpeko can deny Gyarados entry and sash sets can revenge kill Gyarados, and If positioned right Gyarados can break through Eldegoss with just waterfall.

 (Breaking through Eldegoss is easier with rain, but this is an inherently riskier strategy especially if Lum Berry is either absent or consumed. This effectively means Gyarados is able to choose it's own counters.] 

The main thing that makes Gyarados such a threating set-up Sweeper and breaker is it's vast movepool. Waterfall and dragon dance are mandatory. The last two moves lots can be filled with a variety of coverage and/or status moves to suit your teams needs. 

Ddance Sweeper 

Gyarados @ Lum Berry  

Ability: Moxie  

EVs: 252 Atk / 4 SpA / 252 Spe  

Lonely Nature  

- Dragon Dance  

- Waterfall  

- Power Whip  

- Hurricane

 Hurricane ohkos Chesnaught, and Power whip ohkos Gastrodon. This allows Gyarados to nearly effortlessly break through 2 of its most prominent defensive checks. Lumberry allows Gyarados to setup a dragon dance in front of Gastrodon or Chesnaught, and likely sweep with rain up. Lum also allows sets up in front of a Drifblim clicking will-o-wisp. 

The major weakness of this set is that it will struggle into anything that is able to tank 2 waterfalls, including especially physdef Eldegoss and Pelipper. As an alternative to power whip, Stone Ege can be utilized to guarantee the KO against Pelipper with less setup as well as to perform better into Drifblim outside of rain. 

Earthquake is an option for dispatching Pincurchin under similar conditions, and temper flare can be slotted in if Eldegoss haunts your nightmares like it does mine. Substitute with Heavy-Duty-Boots or a damage-boosting item is another solid option over Lumberry. If one turn of flying stab is all you need, then bounce with power herb is your new best friend. Bounce, with its chance of paralysis, also offers another potential out against defensive Unburden Drifblim. If Drifblim is the main concern, then crunch can be utilized instead of stone edge for more consistency (and a decent chance of a defense drop) 

 Crunch is also a very solid neutral option, as it has zero immunities and few resistances in the tier. One of those resistances, though just happens to be the world's least consistent check to ever grace competitive singles, more commonly referred to as "choice scarf Passimian." The unholy love child of borderline unviability and sheer player stubborness, choice scarf Passimian can be a real thorn in unlucky or reckless Gyarados players 'sides. The most damage an adamant choices scarf Passimmian can deal to Gyardos is only 40-73% (not enough to ohko after stealth rock damage). Most of the time, scarf Passimian will be coming in on a +2 atk + 1.5 peed Gyarados. Depending on Evs, item, and weather, Gyarads can sometimes outspeed or Ohko. If it can do neither, and it has sufficient HP, Gyarados can use dragon dance an additional time and become both fast and strong enough to outspeed and ohko Passimmian. The sole obstacle to this outcome would be the 30% chance to flinch from rock slide • More often than not, the Pass immian player will find themselves on the losing side of the interaction, And yet, Passimmian remains the most popular choice scarfer in the tier, primarily because it insists on itself. If I had a statistics degree or a teching credential, I'd elaborate further, but seeing as I'm as lacking in qualifications as passimian is genuine meta viability, I'll leave it at that. 

The only mon a healthy +2 +1 Gyarades should truly fear is December's true king of Gondor and Isildor's heir, Durant. Durant has a myriad of options it can use to make Oyarados regret the day it jumped over that goddamned waterfall.

 Banded Life-orb-Boosted First Impression (with Hustle) is able to reliably deal half health Gyarados (or more) to Gyarados. Focus sash is another threat, and not that uncommon due to Durant's potential as a setup sweeper. And if the Durant isn't Hustle, it's probably serving as the actual best 1 choice scarf user in the tier (with the swarm ability for consistency. (Entruantment ant isn't real, no matter what you say}!) 

An alternative, an Ev spread of 248 + Atk 112 -SpA/ 244 Spe can be utilized if you would rather have an easier time setting up and staying healthy than a guranteed Ohko against Chesnaught. I personally recommend this set as it encourages safer play and allows you to use Gyarados as a means to eliminate Chesnaught as opposed + as a setup Sweeper. The 12-SpA evs on this set, however, affords the best possible odds of Koing Chesnaught without making the most efficient use of EVs. [Yers-75 to odds 8ers-75 to odds 12ers- 81.34 -odds 24 evs- 87.54 -odds] (or use the secret 4 0- evs to really gurantee it) In addition to EV training your Gyarades, teaching him 4 solid moves, and giving him plenty of treats after every practice session, it's essential to train your Gyarados to recognize opportunities to set up while taking minimal or even zero damage. If you play your cards right (or just let an ancient spirit play them for you), your Gyarados can back itself to win entire games. 

The Lum Berry item is one of the most consistent methods of earning these setup opportunities. Positioning Gyarades in front of a status setter in the mid to late game is a phenomenal way to bait a status-inflicting move, as most status spreaders cannot deal sufficient damage with attacking moves to chip Gyarados into manageable range. A prime example of this is everybody's favorite slug, Gastrodon. Gastrodon's comparatively low special attack stat to Gyarados's natural special bulk, combined with its poor offensive type matchup, renders Gastradon a little more than a momentum sink against setup Gyarados. And this is where the power whip more is key to threatening an Ohko at +0, which means that Macargo's actually viable older sibling (Gastrodon) must think twice about staying in or switching out. In a typical game state, the Gyarados player will be in advantage here. An incorrect decision on their part will rarely spell doom as an incorrect decision on their opponent's part would. A full physically defensive Rinda Berry Gastrodon is virtually the only set which can afford to always click clear smog into the not-so-little ex- carp that could. And even then, Gyarados could theoretically have chosen to swap a coverage move for stab if you're feeling bold and really love visiting Nevada). Intuitively, one of the best ways to prevent a Gyarados sweep is to not allow it to come in for free against your Gastrodon. The same holds true both for other defensive Pokemon against Gyarados and in reverse for other offensive Pokemon into Gastrodon. Interestingly, Chesnaught can occupy either role depending on the team. Clear smog Rindo Berry Gastrodon is actually always going to be your friend there, as clear smog should deal enough damage to break substitute on Belly Drum sets.

Written by Typhon

Grammar checked by Essence