I can't help notice how .. "limited" the Ariados page is. I've basically added more detail to it, and added a CB set.
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http://www.smogon.com/dp/pokemon/ariados/
[SET]
Name: Baton Pass
Move 1: Spider Web / Agility
Move 2: Baton Pass
Move 3: Sucker Punch
Move 4: Bug Bite / Toxic Spikes / Endure
Item: Focus Sash / Salac Berry
Ability: Insomnia
Nature: Adamant / Impish
EVs: 4 HP / 252 Atk / 252 Spe
[SET COMMENTS]
<p>Ariados is the only Pokémon (bar Smeargle) to learn both Spider Web and Baton Pass. However, you may prefer to pass Agility due to Ariados' incredibly low Speed, which would make it easier to pull of a Baton Pass. Sucker Punch hits Ghosts and Psychic's hard, and Bug Bite may pick up extra boosts from Liechi or Salac berries, which would come as a welcome boost. However, Toxic Spikes provides more team support, and can help wear things down. It also works well if you trap a Pokémon that does nothing against Ariados, as you can setup with ease. Using Endure with Salac Berry may help pull off a successful Baton Pass. Poison Jab could be used, but is generally seen as a weaker option. You can use an alternate, more defensive EV spread of 220 HP / 252 Def / 36 SpD, which lets you survive a Jolly Choice Band Primape's Stone Edge. It also takes advantage of Ariados' x4 Fighting and Grass resists. Ariados can also run an Impish nature with this defensive EV spread.</p>
[SET]
Name: Choice Band
Move 1: Poison Jab
Move 2: Bug Bite
Move 3: Sucker Punch
Move 4: Pursuit / Toxic Spikes
Item: Choice Band
Ability: Swarm
Nature: Adamant
EVs: 4 HP / 252 Atk / 252 Spe
[SET COMMENTS]
<p>This set takes advantage of Ariados' only decent stat; Attack. Poison Jab provides a decent STAB, and is likely to OHKO many frailer sweepers, such as Swellow and Ninetales (although the latter needs Stealth Rock support). Bug Bite backs it up, while possibly picking up extra boosts. You may get a Swarm boost too. Sucker Punch makes up for Ariados' awful Speed, and will OHKO many weaker Pokémon. The last slot can go for either Pursuit or Toxic Spikes (if you ever find the time to do the latter). Pursuit will do a minimum of 86% to a fleeing Grumpig, and a minimum of 78% to Hypno.</p>
[Other Options]
<p>There aren't many. Agility can work with Life Orb. Shadow Sneak can be used if you are worried about things setting up on Sucker Punch.</p>
[EVs]
<p>Ariados should run 252 Atk and Speed, or use the EV spread 220 HP / 252 Def / 36 SpD. The latter provides more bulk, but the former is more offensive. Impish with the defensive EV spread provides even more bulk on top of this. 172 EVs in Speed can work with Agility; allowing you to outspeed all base 95 Pokémon after a boost.</p>
[Opinion]
<p>Ariados' stats are in general, awful. However, should you pull of a Spider Web pass, Ariados hasn't been useless. His Attack can cause some hurt, provided you aren't taken out first. Insomnia is nice to help take Sleep though, and often helps pull off a Baton Pass.</p>
[Counters]
<p>Most things in general. Steel and Fire types are best. Aggron and other physical walls shrug off the Choice Bander with ease, you just have to be careful of Spider Web. Camerupt and Ninetales can come in moderately easily, and cause pain with their STAB Fire attacks. Aerodactyl can also come in and Taunt Ariados to prevent the Baton Pass, and hit back with its super-effective STAB moves. Damage from Stealth Rock can add up quickly, so try to take advantage of this.</p>
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http://www.smogon.com/dp/pokemon/ariados/

[SET]
Name: Baton Pass
Move 1: Spider Web / Agility
Move 2: Baton Pass
Move 3: Sucker Punch
Move 4: Bug Bite / Toxic Spikes / Endure
Item: Focus Sash / Salac Berry
Ability: Insomnia
Nature: Adamant / Impish
EVs: 4 HP / 252 Atk / 252 Spe
[SET COMMENTS]
<p>Ariados is the only Pokémon (bar Smeargle) to learn both Spider Web and Baton Pass. However, you may prefer to pass Agility due to Ariados' incredibly low Speed, which would make it easier to pull of a Baton Pass. Sucker Punch hits Ghosts and Psychic's hard, and Bug Bite may pick up extra boosts from Liechi or Salac berries, which would come as a welcome boost. However, Toxic Spikes provides more team support, and can help wear things down. It also works well if you trap a Pokémon that does nothing against Ariados, as you can setup with ease. Using Endure with Salac Berry may help pull off a successful Baton Pass. Poison Jab could be used, but is generally seen as a weaker option. You can use an alternate, more defensive EV spread of 220 HP / 252 Def / 36 SpD, which lets you survive a Jolly Choice Band Primape's Stone Edge. It also takes advantage of Ariados' x4 Fighting and Grass resists. Ariados can also run an Impish nature with this defensive EV spread.</p>
[SET]
Name: Choice Band
Move 1: Poison Jab
Move 2: Bug Bite
Move 3: Sucker Punch
Move 4: Pursuit / Toxic Spikes
Item: Choice Band
Ability: Swarm
Nature: Adamant
EVs: 4 HP / 252 Atk / 252 Spe
[SET COMMENTS]
<p>This set takes advantage of Ariados' only decent stat; Attack. Poison Jab provides a decent STAB, and is likely to OHKO many frailer sweepers, such as Swellow and Ninetales (although the latter needs Stealth Rock support). Bug Bite backs it up, while possibly picking up extra boosts. You may get a Swarm boost too. Sucker Punch makes up for Ariados' awful Speed, and will OHKO many weaker Pokémon. The last slot can go for either Pursuit or Toxic Spikes (if you ever find the time to do the latter). Pursuit will do a minimum of 86% to a fleeing Grumpig, and a minimum of 78% to Hypno.</p>
[Other Options]
<p>There aren't many. Agility can work with Life Orb. Shadow Sneak can be used if you are worried about things setting up on Sucker Punch.</p>
[EVs]
<p>Ariados should run 252 Atk and Speed, or use the EV spread 220 HP / 252 Def / 36 SpD. The latter provides more bulk, but the former is more offensive. Impish with the defensive EV spread provides even more bulk on top of this. 172 EVs in Speed can work with Agility; allowing you to outspeed all base 95 Pokémon after a boost.</p>
[Opinion]
<p>Ariados' stats are in general, awful. However, should you pull of a Spider Web pass, Ariados hasn't been useless. His Attack can cause some hurt, provided you aren't taken out first. Insomnia is nice to help take Sleep though, and often helps pull off a Baton Pass.</p>
[Counters]
<p>Most things in general. Steel and Fire types are best. Aggron and other physical walls shrug off the Choice Bander with ease, you just have to be careful of Spider Web. Camerupt and Ninetales can come in moderately easily, and cause pain with their STAB Fire attacks. Aerodactyl can also come in and Taunt Ariados to prevent the Baton Pass, and hit back with its super-effective STAB moves. Damage from Stealth Rock can add up quickly, so try to take advantage of this.</p>