This hasn't taken too long, I've used Qwilfish loads before and some parts are taken from the UU one I did. I've decided to only have Swords Dancer as a set for OU with anything else other options as I seriously see no reason why you would do anything else with Qwilfish in OU than Swords Dance and sweep in the rain. It doesn't have time to set up Spikes, etc with reliability.
STATUS: Done.
http://www.smogon.com/dp/pokemon/qwilfish
Team Options in blue.
[SET]
name: OU Swords Dancer
move 1: Swords Dance
move 2: Waterfall
move 3: Poison Jab
move 4: Explosion
item: Life Orb
ability: Swift Swim
nature: Adamant
evs: 252 Atk / 4 Def / 252 Spe
[SET COMMENTS]
<p>Qwilfish makes a great Swords Dancer in the rain; a +2 STAB Waterfall boosted by the rain leaves a massive dent even in Skarmory, doing 76.3% - 90.1% to maximum HP and Defense variants, meaning it can sometimes OHKO with Stealth Rock support. Poison Jab pairs well with Waterfall, hitting most Pokemon that resist Waterfall. It always OHKOs even the most defensive of Celebi at +2, as well as OHKOing 4 HP Latias, which is outsped in the rain. Explosion finishes off the set by allowing Qwilfish to go out with a bang and do some major damage.</p>
<p>While many would opt to use Kabutops for the higher Attack stat and a STAB Stone Edge, Qwilfish does have some advantages over the prehistoric arthropod. Possibly its biggest advantage over Kabutops is that it can absorb the Toxic Spikes which cripple most Rain Dance teams. It also has a much easier time against Celebi since Kabutops has to use X-Scissor if it wants to OHKO Celebi at +2, meaning it will lose Aqua Jet and have a harder time against Scizor; on the other hand, Poison Jab is a staple move for Qwilfish. Lastly, Qwilfish has access to Explosion, which OHKOs every non Ghost-type in OU after a Swords Dance.</p>
<p>Adamant is the recommended nature as it gives Qwilfish as much power as possible while still being insanely fast in the rain. Running 252 Speed EVs ensures that Qwilfish speed ties with Kingdra, who can easily sweep unprepared Rain Dance teams. There's no point dropping Speed as 264 Speed would be the minimum to outspeed Choice Scarf Gengar and Latias in the rain and those extra HP EVs aren’t worth missing the Speed tie with Kingdra. Jolly can be used, although it is discouraged. It doesn’t let you outrun any notable threats, but could prove useful outside of the rain, allowing Qwilfish to outspeed Adamant Lucario, Jolly Gyarados, and Jolly Mamoswine. Swift Swim is the obvious ability since it doubles Qwilfish’s Speed in the rain. Life Orb is used as Qwilfish needs all the power it can get, while still retaining the freedom of switching between attacks.</p>
<p>When using Qwilfish, your teammates should be one of two things: Rain Dance sweepers or Rain Dance supporters. The best Rain Dance sweeper to support Qwilfish is Ludicolo because Qwilfish has a lot of trouble getting past bulky Water-types, such as Suicune and Vaporeon, whereas Ludicolo’s STAB Grass-type moves can deal with them. Kingdra is a staple on any OU Rain Dance team, and partners up effectively with Qwilfish. The mixed sweeper can clear the way for a Qwilfish sweep by dealing with Gyarados and Salamence, while the special sweeper will appreciate Blissey taken care of and bulky Water-types Exploded on.</p>
<p>The best Rain Dance supporters to Qwilfish are those who can take its weaknesses to Electric-, Ground-, and Psychic-type moves, but also those who can deal with Abomasnow, Hippowdon, and Tyranitar, whose abilities clear the rain. Latias is a great partner as it resists all the weaknesses Qwilfish possesses. Swampert can switch in on Electric-type moves with impunity, and also deals with Tyranitar and Hippowdon. Scizor is another good partner as its Bullet Punch can take out both Tyranitar and Abomasnow. Electric-types, such as Jolteon, Magnezone, Rotom-W, and Zapdos are other great partners to take on the bulky Water-types which trouble Qwilfish, with a 100% accurate STAB Thunder in the rain. Jolteon, Magnezone, and Rotom-W can also take the Electric-type attacks commonly aimed at Qwilfish, while Rotom-W and Zapdos are immune to the Ground-type attacks Qwilfish hates.</p>
[Team Options]
<p>For support options, the first and foremost thing Qwilfish needs is Rain Dance support, since this is what makes it a threat. Many Pokemon can set this up, but for the lead slot, Azelf, Crobat, Electrode, Jirachi, and Zapdos are the best options. For mid-game supporters to set up Rain Dance, Bronzong, Rotom-W, Scizor, Starmie, and Swampert are all reliable options. Stealth Rock, from Pokemon such as Azelf, Bronzong, Jirachi, and Swampert, is also very useful to Qwilfish in helping it against Pokemon such as Skarmory and Swampert. Screen support can be useful since it makes it easier for Qwilfish to set up a Swords Dance. Bronzong, Magnezone, and Rotom-W would be your best options for this. Memento support (from Uxie, for example) can also give Qwilfish an easier time setting up a Swords Dance.</p>
<p>For offensive and defensive support partners, all the previously mentioned Pokemon in the Swords Dancer set work well. The main thing to remember is that they should either be able to set up the rain to support Qwilfish and be able to take the attacks aimed at it or they should be other Swift Swim sweepers that like Qwilfish aim to sweep in the rain.</p>
[Other Options]
<p>Qwilfish can set up Rain Dance itself, but this is better left to faster or bulkier Pokemon; Qwilfish should stick to Swords Dance. It can also utilize both Spikes and Toxic Spikes, but Skarmory and Forretress, for example, do this better in OU. Qwilfish can use Destiny Bond to make an opponent faint if they take out Qwilfish, but you're better off Exploding in OU. Qwilfish has access to Taunt to stop opponents from using status or setting up, but Qwilfish will find very few opportunities to use it. There's Endure/Sub and Flail, but the strong presence of Tyranitar and Hippowdon in OU, as well as priority makes this not worth it. Counter is rather gimmicky, and should only be used with a Focus Sash, but it could surprise some Pokemon. Anything else of note requires Qwilfish to take a hit or be slow (Revenge, Payback, Gyro Ball), which is definitely not acceptable. Aqua Jet could be used as it gives Qwilfish come priority, but that makes it generally outclassed by Kabutops who has a higher Attack stat. Also, Aqua Jet and Swords Dance is an illegal combination, and so this limits Qwilfish's ability to use it effectively in OU.</p>
[EVs]
<p>Just max Attack and Speed. You could drop its Speed down to 264 to just outrun Choice Scarf Gengar and Latias in the rain, but you're better off just Speed tying with Kingdra, as the HP EVs would be insignificant.</p>
[Opinion]
<p>Qwilfish in OU is no joke. Its Attack stat may not be stellar, nor its Speed, but Rain Dance lets it overcome its mediocre Speed stat to become faster than anything commonly used in OU, and the rain helps make Waterfall a truly fearsome attack. Kabutops may have the higher Attack stat, but Qwilfish has many invaluable qualities such as the ability to absorb Toxic Spikes and Explode. You may laugh at first sight, but you won’t be laughing when it proceeds to rip apart your team.</p>
[Counters]
<p>Bulky Water-types are its number one counters. Without a boost, Swampert easily disposes of it with Earthquake, and can even survive if Qwilfish is at +2, although the odds are against it if Stealth Rock is up. Suicune and Vaporeon can take it on if they have Hidden Power Electric or if Qwilfish is weakened, as a +2 Poison Jab only musters a 2HKO. Gyarados and Salamence are great counters as they have Intimidate to weaken the attacks of Qwilfish, while being able to take it out with Earthquake, and all Qwilfish can really do is Explode.</p>
<p>While they are UU and so aren’t too common in OU, Quagsire and Toxicroak still make great counters as they are immune to Water-type moves because of Water Absorb and Dry Skin respectively, and both resist Poison-type moves. Milotic can do well if it has Hidden Power Electric since it has the bulk to take a +2 Poison Jab. Walrein can do very well against it thanks to its high HP and good Defense, but will need Earthquake to hit back or hail needs to be active; Walrein can then slowly weaken down Qwilfish through Substitute and Protect.</p>
STATUS: Done.

http://www.smogon.com/dp/pokemon/qwilfish
Team Options in blue.
[SET]
name: OU Swords Dancer
move 1: Swords Dance
move 2: Waterfall
move 3: Poison Jab
move 4: Explosion
item: Life Orb
ability: Swift Swim
nature: Adamant
evs: 252 Atk / 4 Def / 252 Spe
[SET COMMENTS]
<p>Qwilfish makes a great Swords Dancer in the rain; a +2 STAB Waterfall boosted by the rain leaves a massive dent even in Skarmory, doing 76.3% - 90.1% to maximum HP and Defense variants, meaning it can sometimes OHKO with Stealth Rock support. Poison Jab pairs well with Waterfall, hitting most Pokemon that resist Waterfall. It always OHKOs even the most defensive of Celebi at +2, as well as OHKOing 4 HP Latias, which is outsped in the rain. Explosion finishes off the set by allowing Qwilfish to go out with a bang and do some major damage.</p>
<p>While many would opt to use Kabutops for the higher Attack stat and a STAB Stone Edge, Qwilfish does have some advantages over the prehistoric arthropod. Possibly its biggest advantage over Kabutops is that it can absorb the Toxic Spikes which cripple most Rain Dance teams. It also has a much easier time against Celebi since Kabutops has to use X-Scissor if it wants to OHKO Celebi at +2, meaning it will lose Aqua Jet and have a harder time against Scizor; on the other hand, Poison Jab is a staple move for Qwilfish. Lastly, Qwilfish has access to Explosion, which OHKOs every non Ghost-type in OU after a Swords Dance.</p>
<p>Adamant is the recommended nature as it gives Qwilfish as much power as possible while still being insanely fast in the rain. Running 252 Speed EVs ensures that Qwilfish speed ties with Kingdra, who can easily sweep unprepared Rain Dance teams. There's no point dropping Speed as 264 Speed would be the minimum to outspeed Choice Scarf Gengar and Latias in the rain and those extra HP EVs aren’t worth missing the Speed tie with Kingdra. Jolly can be used, although it is discouraged. It doesn’t let you outrun any notable threats, but could prove useful outside of the rain, allowing Qwilfish to outspeed Adamant Lucario, Jolly Gyarados, and Jolly Mamoswine. Swift Swim is the obvious ability since it doubles Qwilfish’s Speed in the rain. Life Orb is used as Qwilfish needs all the power it can get, while still retaining the freedom of switching between attacks.</p>
<p>When using Qwilfish, your teammates should be one of two things: Rain Dance sweepers or Rain Dance supporters. The best Rain Dance sweeper to support Qwilfish is Ludicolo because Qwilfish has a lot of trouble getting past bulky Water-types, such as Suicune and Vaporeon, whereas Ludicolo’s STAB Grass-type moves can deal with them. Kingdra is a staple on any OU Rain Dance team, and partners up effectively with Qwilfish. The mixed sweeper can clear the way for a Qwilfish sweep by dealing with Gyarados and Salamence, while the special sweeper will appreciate Blissey taken care of and bulky Water-types Exploded on.</p>
<p>The best Rain Dance supporters to Qwilfish are those who can take its weaknesses to Electric-, Ground-, and Psychic-type moves, but also those who can deal with Abomasnow, Hippowdon, and Tyranitar, whose abilities clear the rain. Latias is a great partner as it resists all the weaknesses Qwilfish possesses. Swampert can switch in on Electric-type moves with impunity, and also deals with Tyranitar and Hippowdon. Scizor is another good partner as its Bullet Punch can take out both Tyranitar and Abomasnow. Electric-types, such as Jolteon, Magnezone, Rotom-W, and Zapdos are other great partners to take on the bulky Water-types which trouble Qwilfish, with a 100% accurate STAB Thunder in the rain. Jolteon, Magnezone, and Rotom-W can also take the Electric-type attacks commonly aimed at Qwilfish, while Rotom-W and Zapdos are immune to the Ground-type attacks Qwilfish hates.</p>
[Team Options]
<p>For support options, the first and foremost thing Qwilfish needs is Rain Dance support, since this is what makes it a threat. Many Pokemon can set this up, but for the lead slot, Azelf, Crobat, Electrode, Jirachi, and Zapdos are the best options. For mid-game supporters to set up Rain Dance, Bronzong, Rotom-W, Scizor, Starmie, and Swampert are all reliable options. Stealth Rock, from Pokemon such as Azelf, Bronzong, Jirachi, and Swampert, is also very useful to Qwilfish in helping it against Pokemon such as Skarmory and Swampert. Screen support can be useful since it makes it easier for Qwilfish to set up a Swords Dance. Bronzong, Magnezone, and Rotom-W would be your best options for this. Memento support (from Uxie, for example) can also give Qwilfish an easier time setting up a Swords Dance.</p>
<p>For offensive and defensive support partners, all the previously mentioned Pokemon in the Swords Dancer set work well. The main thing to remember is that they should either be able to set up the rain to support Qwilfish and be able to take the attacks aimed at it or they should be other Swift Swim sweepers that like Qwilfish aim to sweep in the rain.</p>
[Other Options]
<p>Qwilfish can set up Rain Dance itself, but this is better left to faster or bulkier Pokemon; Qwilfish should stick to Swords Dance. It can also utilize both Spikes and Toxic Spikes, but Skarmory and Forretress, for example, do this better in OU. Qwilfish can use Destiny Bond to make an opponent faint if they take out Qwilfish, but you're better off Exploding in OU. Qwilfish has access to Taunt to stop opponents from using status or setting up, but Qwilfish will find very few opportunities to use it. There's Endure/Sub and Flail, but the strong presence of Tyranitar and Hippowdon in OU, as well as priority makes this not worth it. Counter is rather gimmicky, and should only be used with a Focus Sash, but it could surprise some Pokemon. Anything else of note requires Qwilfish to take a hit or be slow (Revenge, Payback, Gyro Ball), which is definitely not acceptable. Aqua Jet could be used as it gives Qwilfish come priority, but that makes it generally outclassed by Kabutops who has a higher Attack stat. Also, Aqua Jet and Swords Dance is an illegal combination, and so this limits Qwilfish's ability to use it effectively in OU.</p>
[EVs]
<p>Just max Attack and Speed. You could drop its Speed down to 264 to just outrun Choice Scarf Gengar and Latias in the rain, but you're better off just Speed tying with Kingdra, as the HP EVs would be insignificant.</p>
[Opinion]
<p>Qwilfish in OU is no joke. Its Attack stat may not be stellar, nor its Speed, but Rain Dance lets it overcome its mediocre Speed stat to become faster than anything commonly used in OU, and the rain helps make Waterfall a truly fearsome attack. Kabutops may have the higher Attack stat, but Qwilfish has many invaluable qualities such as the ability to absorb Toxic Spikes and Explode. You may laugh at first sight, but you won’t be laughing when it proceeds to rip apart your team.</p>
[Counters]
<p>Bulky Water-types are its number one counters. Without a boost, Swampert easily disposes of it with Earthquake, and can even survive if Qwilfish is at +2, although the odds are against it if Stealth Rock is up. Suicune and Vaporeon can take it on if they have Hidden Power Electric or if Qwilfish is weakened, as a +2 Poison Jab only musters a 2HKO. Gyarados and Salamence are great counters as they have Intimidate to weaken the attacks of Qwilfish, while being able to take it out with Earthquake, and all Qwilfish can really do is Explode.</p>
<p>While they are UU and so aren’t too common in OU, Quagsire and Toxicroak still make great counters as they are immune to Water-type moves because of Water Absorb and Dry Skin respectively, and both resist Poison-type moves. Milotic can do well if it has Hidden Power Electric since it has the bulk to take a +2 Poison Jab. Walrein can do very well against it thanks to its high HP and good Defense, but will need Earthquake to hit back or hail needs to be active; Walrein can then slowly weaken down Qwilfish through Substitute and Protect.</p>