When one looks at Ninetales, the first thing to come to mind is its relative lack of utility outside of Drought. Ninetales is fairly useless outside of its ability, so the sun it provides should be the only reason to run it. While Ninetales doesn't have an expansive movepool or a good stat distribution, it can run a few viable sets that allow it to just barely pull its weight. If you want to pack Ninetales on a team, you need to make sure that you provide adequate support to keep Ninetales alive, as sun teams are generally dependent on Drought support.
While it might seem strange to use a defensive set on a Fire-type, especially one that isn't all that bulk, Ninetales is the MVP of a sun team, as it brings the sun the team relies on. Many sun teams fall flat on their face with another weather in play, so it is imperative for Ninetales to outlast opposing weather inducers. However, opposing weather teams with Dugtrio greatly threaten it. This Ninetales can survive an Earthquake from non-Choice Band Dugtrio, which helps mitigate this worry. Additionally, having a good pivot is always handy, and Ninetales fulfills that role decently. Ninetales can switch into most Grass-, Ice-, Fire-, and Bug-type attacks, as well as Scalds from bulky Water-types. Ninetales still isn't that bulky though, so invest sun-boosted Fire-type attacks from the likes of Darmanitan, Victini, and Volcarona will still hurt.
Flamethrower occupies the first slot as the STAB move of choice, sporting perfect accuracy and decent power in sun. It allows Ninetales to wear down Pokemon with something other than residual damage and prevents it from being Taunt or setup bait. Next, Will-O-Wisp lets Ninetales check a ton of physical attackers, such as Dragonite, by outspeeding and crippling them. It also gives Ninetales a way to beat Dugtrio if you can predict its switch in; although Will-O-Wisp's accuracy is not so great, its huge potential reward makes it worth the risk. Sunny Day is completely irreplaceable, as it steals the momentum back from the switch in of an opposing weather inducer; seizing this momentum gives you an immediate advantage and forces your opponent to rethink their game plan. The last slot is a toss-up between two moves. Roar is usually preferred for deterring setup sweepers, especially SubCM Latias, which is a huge threat to most sun teams, and providing yet another way to combat Dugtrio. Toxic is another option that enables Ninetales to cripple opposing Politoed, Tyranitar, and Hippowdon that just love to switch into it. Hypnosis is another risky but rewarding option, particularly if you manage to catch a weather inducer, a menacing threat, or—guess who—Dugtrio. The final option listed is Substitute, and with good reason. It eases worry against Dugtrio, aids in spreading burn, and lets Ninetales use Sunny Day against Tyranitar. Jirachi, Ferrothorn, and Forretress are just a few Pokemon that Ninetales can set up a free Substitute on. All of these moves are excellent; pick the one that is best for your team.Team Options & Additional Comments >>>
While keeping Ninetales alive for as long as possible is certainly important, it requires quite a bit of support to take hits on its own. Additionally, it has difficulty winning weather wars by itself. However, with an offensive set, Ninetales can both win the weather war and pose an offensive threat. While it doesn't hit that hard with base 81 Special Attack, sun-boosted Fire Blast hits everything it needs to. The offensive presence pushes aside the need for Dugtrio, who is commonly run with defensive Ninetales to make up for its lack thereof. Be sure to make note of this in not always using Dugtrio, otherwise you have an inferior Ninetales that can't take a strong attack to save its life.
SolarBeam is the main draw of this set; 2HKOing Tyranitar and Politoed is no small feat. It also hits most Water-types for decent damage, so it isn't limited in use to just weather inducers. However, its major fault is that it leaves Ninetales defenseless if another weather comes into play. This is where Sunny Day comes in; if you can pull it off as Tyranitar or Politoed comes in, they either switch out or foolishly stay in, only to lose a large amount of health to SolarBeam. However, unlike the defensive set, there is no margin for error when using Sunny Day. One misprediction will leave Ninetales helpless to do anything; thus, you must be aggressive in your use of the move. Next on the highlight reel is Fire Blast. Fire Blast hits considerably hard with 252 Special Attack EVs and sun backing it. The power is not amazing but gets the job done; it 2HKOes frail resists and most neutrally hit offensive Pokemon.
The last slot has quite a few viable options. Hidden Power Ice is the preferred choice to hit Dragon-types hard as well as OHKO Landorus-T and Gliscor without the risk of missing. Will-O-Wisp is an amazing move on Ninetales because of its potency against physical attackers that would otherwise be able to defeat Ninetales with ease. The final option is Nasty Plot, which might seem to be an April Fools' joke on a Pokemon with base 81 Special Attack; however, this is not the case. In sun, a boosted Fire Blast 2HKOes Blissey, which is no small feat for a special attacker. A boosted SolarBeam can OHKO Tyranitar and Politoed, Ninetales's two worst foes. Nonetheless, it cannot be emphasized enough that Ninetales is not a sweeper; it's a utility attacker and should be played as to its strengths; bypassing opposing weather starters while also maintaining an acceptable offensive presence. Be sure to use Air Balloon with Nasty Plot, by the way, since it provides a nice buffer against Dugtrio, Landorus-T, and other Ground-types, as well as Earthquake Dragonite, making it easier to set up.Team Options & Additional Comments >>>
There are a few sets that Ninetales used to be able to run effectively but have declined in use since the release of BW2. One of these is Choice Specs, which makes Fire Blast really pack a punch. However, being locked into one move is terrible for a Pokemon that needs to maintain versatility in attacking, and Ninetales still isn't all that powerful. Similarly, a pure Nasty Plot set with Energy Ball over SolarBeam and Hidden Power Ice over Sunny Day might seem viable, but Ninetales fails to sweep effectively, and Nasty Plot only works with Sunny Day alongside it. If you ever want to run such a set, Dugtrio support is essential to prevent Heatran from being an issue. A Calm Mind booster is another of those sets; in theory, it should allow Ninetales to tank hits and dish them out, but it doesn't quite work that in practice. Multiple boosts are needed to accomplish that goal, and Ninetales has difficulty setting up that many boosts before fainting. The last set is one with 252 Speed EVs and a Timid nature utilizing Disable. À la SubDisable Gengar, Disable could mess with Pokemon that only have one move with which to hit Ninetales hard. However, unlike Gengar, Ninetales cannot to take sufficient advantage of the free turn(s) it might gain, thus it is inferior to any of Ninetales's other options. Toxic could be used in place of Will-O-Wisp as a status move to deter bulky Water-types and weather inducers from switching into Ninetales. On the other hand, it lacks the crippling halving of Attack that Will-O-Wisp boasts, making it a much less effective option overall.
Checks and Counters
The best form of defense against Ninetales is another weather starter, as Ninetales is used solely for sun. If sun is taken off the field, sun teams will be immediately crippled. The two biggest threats that come to mind are Tyranitar, who can threaten to OHKO it with its powerful STAB Rock-type attacks or pick it off with Pursuit, and Politoed who can decimate it with its drizzle boosted Water-type moves. However, Ninetales does have some sort of defense against the two weather starters: both are 2HKOed by SolarBeam, while Tyranitar is also crippled by Will-O-Wisp. Ninetales can also use Sunny Day as they switch in to regain momentum. In short, weather inducers have to be careful against Ninetales, especially offensive variants. The only weather inducer that can switch in risk-free against most Ninetales is Hippowdon, but it can be silenced by Nasty Plot-boosted SolarBeam. If you don't want to have to worry about Ninetales dealing heavy damage to your weather inducer, Dugtrio is the best way to go, as it beats all but Substitute and Air Balloon variants with a little prior damage.
Other than weather inducers, there are a few Pokemon that can beat Ninetales. If you want to completely wall it, Blissey and Chansey are your best friends, as they can take any hit and slowly kill it with Toxic and Seismic Toss. Blissey would do well to watch out for Nasty Plot-boosted Fire Blast, however. Tentacruel also walls it and is able to set up Toxic Spikes, Toxic Ninetales directly, or use Rapid Spin, all for free. Heatran also walls Ninetales and can set up Stealth Rock or straight-up attack with Earth Power. The defensive set is fair game for Gastrodon, but note that the offensive set would OHKO it with SolarBeam if it attempted to take a hit. Terrakion can take any attack other than SolarBeam and OHKO with Stone Edge or Close Combat. Volcarona can set up for free and demolish Ninetales; sun-boosted Fire Blast and Hidden Power Rock 2HKO Ninetales even without Quiver Dance boosts. Even defensive Ninetales has a small chance to be OHKOed by +1 Hidden Power Rock, while offensive variants are always OHKOed by both +1 Hidden Power Rock and +1 Fire Blast. Victini always OHKOes offensive Ninetales with Choice Band V-create and defensive variants over half the time, while taking a pittance from any attacks Ninetales might throw at it. Defensive variants are also easily taken care of by Gliscor.
Other than opposing weather, Dragon-types are the best way to defeat Ninetales. Kyurem-B can take anything Ninetales has other than a burn and blast it to pieces. Garchomp is similar; Yache Berry variants can take even Hidden Power Ice. Latios and Latias also wall and can KO Ninetales. Dragon Dance set-up sweepers that carry Substitute or hold a Lum Berry can set up on and destroy Ninetales along with its teammates. These include Substitute + Dragon Dance Gyarados, Lum Berry Dragon Dance Haxorus, Lum Berry Dragon Dance Dragonite, and Substitute + Dragon Dance Dragonite. These Pokemon only win if Ninetales does not carry Roar, however. Salamence can also beat Ninetales, no matter what the set—Dragon Dance, mixed, Choice Scarf, it doesn't matter.
As you can see, beating Ninetales is quite easy. Even if you don't have any of these Pokemon, you can always resort to pounding Ninetales with powerful attacks or hitting it with priority from Breloom or Choice Band Dragonite.