Note this is my 1st guide^^
Marathon
Ability: Unlimited Sprint
Pro: + Climb obstacles faster
Unlock Level: Start
Extras: There is no limit to how far you can sprint with Marathon. Time taken to climb objects is cut in half with Marathon Pro.
* Pro I - Run 1 mile while using Marathon - 500 XP
* Pro II - Run 5 miles while using Marathon - 1,000 XP
* Pro III - Run 10 miles while using Marathon - 2,500 XP
* Pro IV - Run 26 miles while using Marathon - 5,000 XP (unlocks Marathon Pro)
* Pro V - Run 52 miles while using Marathon - 10,000 XP
* Pro VI - Run 104 miles while using Marathon - 10,000 XP
Sleight of Hand
Ability: Faster reload time
Pro: + Aim down sights faster
Unlock Level: Start
Extras: Sleight of Hand cuts reload time in half. Sleight of Hand Pro cuts the time it takes to aim in and out of the sight in half.
* Pro I - Get 15 kills while using Sleight of Hand - 500 XP
* Pro II - Get 30 kills while using Sleight of Hand - 1,000 XP
* Pro III - Get 60 kills while using Sleight of Hand - 2,500 XP
* Pro IV - Get 120 kills while using Sleight of Hand - 5,000 XP (unlocks Sleight of Hand Pro)
* Pro V - Get 300 kills while using Sleight of Hand - 10,000 XP
* Pro VI - Get 750 kills while using Sleight of Hand - 10,000 XP
Scavenger
Ability: Fully resupply from dead bodies
Pro: + Extra magazines
Unlock Level: 13
Extras: Scavenger will automatically resupply if empty on any of the following: Bullets, Equipment, or Gun Attachments (only 1 of Equipment or Grenade Launchers). Scavenger Pro starts you with full ammunition.
* Pro I - Resupply 10 times while using Scavenger - 500 XP
* Pro II - Resupply 25 times while using Scavenger - 1,000 XP
* Pro III - Resupply 50 times while using Scavenger - 2,500 XP
* Pro IV - Resupply 100 times while using Scavenger - 5,000 XP (unlocks Scavenger Pro)
* Pro V - Resupply 250 times while using Scavenger - 10,000 XP
* Pro VI - Resupply 500 times while using Scavenger - 10,000 XP
Bling
Ability: Dual attachments on primary weapon
Pro: + Dual attachments on secondary weapon
Unlock Level: 21
Extras: Cannot have two different scopes. Snipers can have two attachments + a regular sniper scope (ex: Scope, Heartbeat Sensor, Silencer).
* Pro I - Get 25 kills with two weapon attachments - 500 XP
* Pro II - Get 50 kills with two weapon attachments - 1,000 XP
* Pro III - Get 100 kills with two weapon attachments - 2,500 XP
* Pro IV - Get 200 kills with two weapon attachments - 5,000 XP (unlocks Bling Pro)
* Pro V - Get 450 kills with two weapon attachments - 10,000 XP
* Pro VI -Get 900 kills with two weapon attachments - 10,000 XP
One Man Army
Ability: Swap classes at any time
Pro: + Swap classes faster
Unlock Level: 45
Extras: Class change takes 6 seconds using One Man Army. One Man Army Pro class change takes 3 seconds. One Man Army takes the place of a Secondary Weapon. If switched to a class without One Many Army, kill challenges are still completed in that lifetime.
* Pro I - Get 15 kills while using One Man Army - 500 XP
* Pro II - Get 30 kills while using One Man Army - 1,000 XP
* Pro III - Get 60 kills while using One Man Army - 2,500 XP
* Pro IV - Get 120 kills while using One Man Army - 5,000 XP (unlocks One Man Army Pro)
* Pro V - Get 300 kills while using One Man Army - 10,000 XP
* Pro VI - Get 750 kills while using One Man Army - 10,000 XP
Tier 2 (Red)
Stopping Power
Ability: Increased bullet damage
Pro: + Increased bullet damage to cars and killstreaks
Unlock Level: Start
Extras: Stopping Power multiplies bullet damage x1.4. Stopping Power Pro multiplies bullet damage against vehicles x1.4.
* Pro I - Get 30 kills while using Stopping Power - 500 XP
* Pro II - Get 60 kills while using Stopping Power - 1,000 XP
* Pro III - Get 120 kills while using Stopping Power - 2,500 XP
* Pro IV - Get 250 kills while using Stopping Power - 5,000 XP (unlocks Stopping Power Pro)
* Pro V - Get 500 kills while using Stopping Power - 10,000 XP
* Pro VI - Get 1,000 kills while using Stopping Power - 10,000 XP
Lightweight
Ability: Move faster
Pro: + Bring sights up quicker after sprinting
Unlock Level: Start
Extras: Lightweight multiplies the movement speed by 1.1 (8% or 10% depending on the weight of the weapon carried). Lightweight Pro cuts the time to go from sprinting to being able to fire in half.
* Pro I - Travel 2 mile using Lightweight - 500 XP
* Pro II - Travel 8 miles using Lightweight - 1,000 XP
* Pro III - Travel 15 miles using Lightweight - 2,500 XP
* Pro IV - Travel 30 miles using Lightweight - 5,000 XP (unlocks Lightweight Pro)
* Pro V - Travel 100 miles using Lightweight - 10,000 XP
* Pro VI - Travel 250 miles using Lightweight - 10,000 XP
Hardline
Ability: Killstreak rewards require one less kill
Pro: + Deathstreak rewards require one less death
Unlock Level: 9
Extras: Hardline cuts all killstreaks by 1 kill. Hardline Pro cuts all deathstreaks by one death.
* Pro I - Get 3 killstreaks while using Hardline - 500 XP
* Pro II - Get 10 killstreaks while using Hardline - 1,000 XP
* Pro III - Get 20 killstreaks while using Hardline - 2,500 XP
* Pro IV - Get 40 killstreaks while using Hardline - 5,000 XP (unlocks Hardline Pro)
* Pro V - Get 100 killstreaks while using Hardline - 10,000 XP
* Pro VI - Get 250 killstreaks while using Hardline - 10,000 XP
Cold Blooded
Ability: Undetectable by UAV, air support, sentry guns, and thermal scopes
Pro: + No red crosshair or name when targeted
Unlock Level: 25
Extras: Cold Blooded makes no enemy air vehicle able to see you. You will not be outlined by red when the enemy is controlling a Predator Missile, Chopper Gunner, or AC130. With Cold Blooded Pro enemies will not see your name when they look at you from close range.
* Pro I - Destroy 3 enemy killstreak rewards while using Cold Blooded - 500 XP
* Pro II - Destroy 10 enemy killstreak rewards while using Cold Blooded - 1,000 XP
* Pro III - Destroy 20 enemy killstreak rewards while using Cold Blooded - 2,500 XP
* Pro IV - Destroy 40 enemy killstreak rewards while using Cold Blooded - 5,000 XP (unlocks Cold Blooded Pro)
* Pro V - Destroy 100 enemy killstreak rewards while using Cold Blooded - 10,000 XP
* Pro VI - Destroy 250 enemy killstreak rewards while using Cold Blooded - 10,000 XP
Danger Close
Ability: Increases explosive weapons' damage
Pro: + Extra air support damage
Unlock Level: 33
Extras: Danger Close increases explosive weapon damage by 1.4. Danger Close Pro increases all killstreak rewards damage by 1.4. Applied to all killstreaks that do damage.
* Pro I - Get 10 kills with explosives while using Danger Close - 500 XP
* Pro II - Get 25 kills with explosives while using Danger Close - 1,000 XP
* Pro III - Get 50 kills with explosives while using Danger Close - 2,500 XP
* Pro IV - Get 100 kills with explosives while using Danger Close - 5,000 XP (unlocks Danger Close Pro)
* Pro V - Get 250 kills with explosives while using Danger Close - 10,000 XP
* Pro VI - Get 500 kills with explosives while using Danger Close - 10,000 XP
Commando
Ability: Increased melee distance
Pro: + No falling damage
Unlock Level: Start
* Pro I - Get 2 knife kills while using Commando - 500 XP
* Pro II - Get 5 knife kills while using Commando - 1,000 XP
* Pro III - Get 10 knife kills while using Commando - 2,500 XP
* Pro IV -Get 20 knife kills while using Commando - 5,000 XP
* Pro V -Get 50 knife kills while using Commando - 10,000 XP
* Pro VI -Get 100 knife kills while using Commando - 10,000 XP
Steady Aim
Ability: Increased hip-fire accuracy
Pro: + Hold breath longer while sniping
Unlock Level: Start
* Pro I - Get 10 hip-fire kills while using Steady Aim - 500 XP
* Pro II -Get 20 hip-fire kills while using Steady Aim - 1,000 XP
* Pro III -Get 40 hip-fire kills while using Steady Aim - 2,500 XP
* Pro IV -Get 80 hip-fire kills while using Steady Aim - 5,000 XP
* Pro V - Get 200 hip-fire kills while using Steady Aim - 10,000 XP
* Pro VI -Get 500 hip-fire kills while using Steady Aim - 10,000 XP
Scrambler
Ability: Scrambles radar of enemies close by
Pro: + Delay enemy Claymore explosions
Unlock Level: 17
* Pro I - Get 5 close range kills while using Scrambler - 500 XP
* Pro II - Get 10 close range kills while using Scrambler - 1,000 XP
* Pro III - Get 25 close range kills while using Scrambler - 2,500 XP
* Pro IV - Get 50 close range kills while using Scrambler - 5,000 XP
* Pro V - Get 125 close range kills while using Scrambler - 10,000 XP
* Pro VI - Get 250 close range kills while using Scrambler - 10,000 XP
Ninja
Ability: Undetectable to heartbeat sensors
Pro: + Silent footsteps
Unlock Level: 29
* Pro I - Get 5 close range kills while using Ninja - 500 XP
* Pro II - Get 10 close range kills while using Ninja - 1,000 XP
* Pro III - Get 25 close range kills while using Ninja - 2,500 XP
* Pro IV - Get 50 close range kills while using Ninja - 5,000 XP
* Pro V - Get 125 close range kills while using Ninja - 10,000 XP
* Pro VI - Get 250 close range kills while using Ninja - 10,000 XP
Sitrep
Ability: Reveals enemy explosives and tactical insertions in red
Pro: + Louder enemy footsteps
Unlock Level: 37
* Pro I - Destroy 15 enemy devices or tactical insertions while using Sitrep - 500 XP
* Pro II - Destroy 30 enemy devices or tactical insertions while using Sitrep - 1,000 XP
* Pro III - Destroy 60 enemy devices or tactical insertions while using Sitrep - 2,500 XP
* Pro IV - Destroy 120 enemy devices or tactical insertions while using Sitrep - 5,000 XP
* Pro V - Destroy 300 enemy devices or tactical insertions while using Sitrep - 10,000 XP
* Pro VI -Destroy 750 enemy devices or tactical insertions while using Sitrep - 10,000 XP
Last Stand
Ability: Survive on the ground for 10 seconds after being shot down. A pistol will automatically be your weapon of defense
Pro: Use equipment along with your pistol
Unlock Level: 41
* Pro I - Get 2 kills while in Last Stand - 500 XP
* Pro II - Get 5 kills while in Last Stand - 1,000 XP
* Pro III - Get 10 kills while in Last Stand - 2,500 XP
* Pro IV - Get 20 kills while in Last Stand - 5,000 XP
* Pro V - Get 50 kills while in Last Stand - 10,000 XP
* Pro VI - Get 100 kills while in Last Stand - 10,000 XP
Hope it helps