Butterfree has never been a premier choice for competitive battlers, as her poor stats, hideous typing, Stealth Rock weakness, and shallow movepool have prevented her from being a decent Pokemon. However, she has become noticeably better throughout the generations: in ADV, she received Compoundeyes which remedied Sleep Powder and Stun Spore's accuracy problems, and DPP introduced the Focus Sash and Choice Scarf, which gave her more opportunities to use her status moves. But while Butterfree has had a niche in the last two generations as the only Pokemon with a 97.5% accurate Sleep Powder and Stun Spore, she has never really been able to shine in the spotlight of any tier. Now, BW has once again given her some useful tools which have finally given her the chance to shine. First of all, Butterfree has gained Quiver Dance, and with it, she finally has a way to sweep the opposition. Additionally, the Dream World has given Butterfree the Tinted Lens ability, which allows her to circumvent her lack of coverage and sweep with Bug Buzz. To top it all off, Venomoth is banned from RU, so Butterfree is the sole Bug-type that has access to both Quiver Dance and Sleep Powder. While Butterfree is still a poor Pokemon in many ways, and she faces stiff competition from the likes of Quiver Dancing Bug-types and Lilligant, she occupies a few niches in RU as either a reliable status spreader or a lethal Quiver Dance sweeper, and she can be very successful at those niches with a little support.
With access to the picture-perfect combination of Sleep Powder, Quiver Dance, and Tinted Lens, Butterfree is perfectly capable of sweeping the opposing team. Butterfree is the only Bug-type in RU who receives the combination of Sleep Powder and Quiver Dance, and her access to Sleep Powder makes her arguably the best Bug-type Quiver Dancer in RU. While Butterfree does face some heavy competition in Lilligant, Butterfree's abilities set her apart, as Tinted Lens allows Butterfree to rely solely on Bug Buzz for coverage, freeing up room for Substitute, while Compoundeyes nearly guarantees that her Sleep Powder will hit the foe. Additionally, Butterfree is able to outspeed every unboosted Pokemon in the RU metagame after one Quiver Dance, bar Accelgor, Ninjask, and Electrode, making her difficult to revenge kill after a single boost. With little support, Quiver Dance Butterfree is very capable of freely slicing her way through the opposing team like a hot knife through butter.
Sleep Powder is key to this set, as Butterfree's main way to set up on an opponent is to put them to sleep. It is usually a safe option to simply throw out first when Butterfree is sent out, as BW's sleep mechanics basically guarantee that a sleeping Pokemon is effectively knocked out. However, while Sleep Powder is a key weapon in Butterfree's arsenal, note that once Butterfree has put a Pokemon to sleep, she will be unable to do so again until said Pokemon has woken up or fainted, due to Sleep Clause. As such, sometimes it is better to simply set up a Substitute instead (assuming Butterfree is facing a slower opponent), and hope the opponent switches from the threat of Sleep Powder. This allows Butterfree to save her Sleep Powder from being wasted on a Pokemon that would serve as sleep fodder, and she can then react appropriately. If the opponent merely switched in a Pokemon whom she cannot beat, such as Haze Cryogonal, Butterfree should simply use Bug Buzz to deal a little damage, then switch out. However, against other opponents, Butterfree will have a huge advantage if she has a Substitute up, as she has a variety of options at that point. This can vary from putting a dangerous Pokemon to sleep with Sleep Powder, Quiver Dancing to set up on a Pokemon who Butterfree can deal with easily, or just using Bug Buzz to deal some damage. Even if the opponent stayed in and attacked, Butterfree will only lose 25% of her health thanks to Substitute. Choosing between using Sleep Powder or using Substitute is an important choice, as it will determine how effective Butterfree will be for the rest of the match.
Quiver Dance is Butterfree's necessary boosting move, and Butterfree will quickly become difficult to deal with once she has accrued a few boosts. As Bug Buzz is a relatively decent STAB move to fall back upon, especially with Tinted Lens backing it up, Butterfree can become a considerable threat to the opponent after a single Quiver Dance. Do note however, that Butterfree's Special Attack stat is rather mediocre, so multiple Quiver Dances may be needed to sweep. Pokemon such as Moltres can wall Butterfree, so you can opt to use a coverage move such as Hidden Power Rock instead of Substitute, though keep in mind that this makes Butterfree significantly more vulnerable to priority and revenge killers.Team Options & Additional Comments >>>
Butterfree's unique access to Compoundeyes, Sleep Powder, and Stun Spore allow her to be a very reliable status spreader. The accuracy boost that Compoundeyes provides buffs the accuracy of both Sleep Powder and Stun Spore to 97.5%, which means that Butterfree is almost guaranteed to have her status move hit when given the chance. Unfortunately, Butterfree is usually both frail and relatively slow, so she is often unable to do so easily. With a Choice Scarf equipped, however, Butterfree outspeeds the entire unboosted RU metagame bar Accelgor, Ninjask, and Electrode; this gives her more chances to use her status moves, though it does have the drawback of locking Butterfree into a single move.
As always, Sleep Powder is the key move on this set, and as sleep is more deadly than ever in BW, Butterfree can incapacitate a foe for the rest of the match when played correctly. Unfortunately, Sleep Powder has always been Butterfree's staple move, so many opponents will simply switch in their least useful Pokemon, or a Sleep Talker, to take the Sleep Powder. In an attempt to deal with this, U-turn is useful to scout for any such Pokemon. U-turn will also keep the momentum of the match in your favor if the opponent switches, which is useful on offensive teams. Stun Spore is an alternative status to spread over opposing teams to cripple fast sweepers permanently, and few Pokemon are immune to it, unlike Thunder Wave. Toxic is another option to cripple walls, but Stun Spore is generally more useful. Bug Buzz gives Butterfree a fairly strong STAB option that allows her to serve as a revenge killer in some scenarios. For example, Bug Buzz OHKOes Sceptile after Stealth Rock, and 2HKOes Galvantula and other frail Pokemon.Team Options & Additional Comments >>>
Unfortunately, Butterfree is fairly one-dimensional, as her movepool is pitifully shallow. Butterfree has access to alternative special attacks such as Shadow Ball, Psychic, Hidden Power Flying, and Energy Ball, but these moves cannot sufficiently damage most of the Pokemon who can wall her. She also is capable of utilizing support options such as Rain Dance, Sunny Day, and Tailwind. However, due to her poor stats, she is unable to use these options as well as a Pokemon such as Uxie, though she does have a very reliable Sleep Powder to compensate. If you wish to increase Butterfree's longevity, Roost is a viable option, though Butterfree is so frail that it usually isn't worth sacrificing a moveslot for it. You can also try using Butterfree in the lead position with a Focus Sash, but because of Team Preview, Butterfree is significantly more prone to Taunt.
Checks and Counters
As threatening as Butterfree can be, Butterfree has a few crippling flaws. Even though she might not seem like it when she manages to tear through your team, she is still a delicate butterfly that is frail, slow, and weak without a boost. Additionally, she is severely crippled by Stealth Rock, so keeping it on the field is the first step you should take towards countering her. With Stealth Rock up, she loses the ability to switch into weaker attacks, and her trainer is immediately pressured into making the right move as at 50% HP, Butterfree dies to anything aside from a Caterpie's Tackle. Thus, keeping Stealth Rock up is the necessary step to take to make it less likely that Butterfree will manage a sweep.
Even with Stealth Rock up, Butterfree can still manage to pull her weight as she still has the threat of Sleep Powder to keep you on your toes. The best way to deal with this is to pack a Sleep Talk user on your team, such as Emboar, Hariyama, or Escavalier. However, make sure that you also have a phazer, as Sleep Talk can be unreliable, and this can sometimes allow Butterfree to set up on the Pokemon with Sleep Talk. If you do not have a Sleep Talker, Butterfree becomes more of an issue. Usually, it is fairly safe to sacrifice a bulky Pokemon or one which isn't very useful against the opponent to Butterfree's sleep. Unfortunately, this is still easily thwarted by good prediction, so sometimes, it is necessary to run two counters to Butterfree: one to sacrifice to sleep, and one to actually beat her. Fortunately, Butterfree is fairly weak and RU has a collection of great special walls that aren't afraid to wall her, including Altaria, Clefable, Escavalier, Cryogonal, Ferroseed, Gallade, Hitmonchan, Mandibuzz, and Steelix. Most teams often have at least one of these Pokemon as they are fairly useful overall.
While Butterfree can be bothersome for offensive teams, she is still very manageable. Though it is significantly less likely for offensive teams to have something that walls Butterfree, they can easily prevent her from getting in a Quiver Dance. Even after a Quiver Dance, Butterfree is outsped by common Pokemon such as Choice Scarf Rotom and Primeape, in addition to Accelgor and Aerodactyl. Furthermore, she is vulnerable to priority, so Pokemon such as Entei, Hitmonlee and Hariyama can check her. However, offensive teams are weak to Sleep Powder, and once Choice Scarf Pokemon and priority have been removed, she finds it easier to sweep due to most offensive teams' lack of bulk.