This is pretty much the only Ambipom I'd use in the current meta. With Spiritomb everywhere Ambipoms get crippled early on because everyone thinks spamming Fake Out is useful while being met with a Pursuit-happy Tomb, Rhyperior, etc.. Mini rant there but CB definitely deserves to be on site.
http://www.smogon.com/dp/pokemon/ambipom
Name: Choice Band
move 1: Return
move 2: U-turn
move 3: Pursuit
move 4: Low Kick
Item: Choice Band
Nature: Jolly
EVs: 252 Atk / 4 SpD / 252 Spe
Ability: Technician
Why this set deserves to be on-site:
-Ambipom's high Speed and good offensive power allows it to act as a great revenge killer
-Ambipom has great utility in its moves. U-turn is a great scouting move to rack up damage and lets it pull off something like Scyther, albeit weaker but can abuse it more due to neutrality to SR.
-Pursuit coupled with its high speed allows it to eliminate Ghost-types like Mismagius and Rotom.
-Great lure to eliminate Steel- or Rock-types for teammates
Additional comments:
-Other move options. Mainly Payback but it's a lesser option.
-Still works decently as a lead
-Great late game cleaner
Teammates and Counters:
-Pokemon that hate Steel- or Rock-types (depending on last move of choice). Swellow, Scyther, Arcanine, and Venusaur love a Registeel or Rhyperior out of the way.
-Fighting types like Hitmonlee and Hitmontop enjoy Mismagius and Rotom out of the way, and they both can take down Steel- and Rock-types to aid Ambipom.
-A status absorber (Will-o-Wisp). Houndoom, Arcanine, and Restalk Milotic work well.
-Prediction is the number one counter. Rhyperior can switch-in on most moves but hates being nailed by Seed Bomb, Ghosts like switching on Return, etc..
-Spiritomb, and bulky Pokemon like Tangrowth, Weezing, etc...

http://www.smogon.com/dp/pokemon/ambipom
Name: Choice Band
move 1: Return
move 2: U-turn
move 3: Pursuit
move 4: Low Kick
Item: Choice Band
Nature: Jolly
EVs: 252 Atk / 4 SpD / 252 Spe
Ability: Technician
Why this set deserves to be on-site:
-Ambipom's high Speed and good offensive power allows it to act as a great revenge killer
-Ambipom has great utility in its moves. U-turn is a great scouting move to rack up damage and lets it pull off something like Scyther, albeit weaker but can abuse it more due to neutrality to SR.
-Pursuit coupled with its high speed allows it to eliminate Ghost-types like Mismagius and Rotom.
-Great lure to eliminate Steel- or Rock-types for teammates
Additional comments:
-Other move options. Mainly Payback but it's a lesser option.
-Still works decently as a lead
-Great late game cleaner
Teammates and Counters:
-Pokemon that hate Steel- or Rock-types (depending on last move of choice). Swellow, Scyther, Arcanine, and Venusaur love a Registeel or Rhyperior out of the way.
-Fighting types like Hitmonlee and Hitmontop enjoy Mismagius and Rotom out of the way, and they both can take down Steel- and Rock-types to aid Ambipom.
-A status absorber (Will-o-Wisp). Houndoom, Arcanine, and Restalk Milotic work well.
-Prediction is the number one counter. Rhyperior can switch-in on most moves but hates being nailed by Seed Bomb, Ghosts like switching on Return, etc..
-Spiritomb, and bulky Pokemon like Tangrowth, Weezing, etc...