These trophies are a part of the Siege expansion pack and do not count towards the Uncharted 2: Among Thieves platinum trophy.
NOTE: I for one will be more than willing to help anyone out in obtaining the co-op trophies. I'm sure your fellow Cruxis members are willing as well.
You Can't Break Me
Complete all three co-op objective maps on crushing difficulty
The three co-op maps are as follows:
The Sanctuary
The Village
Nepal Warzone
Simply complete all three objective maps on crushing difficulty. You unlock crushing difficulty by completing the map on hard difficulty. Teamwork is key in beating these levels. Stay close to your teammates and make sure to help them out if they've fallen or are being choked by an enemy.
Under Siege
Complete wave ten in one siege game
Siege is probably the easiest co-op game mode. Make sure you stay inside the circle at all times (you'll know all your teammates are in the circle if the flame and perimeter are green) and don't go outside of the circle to get kills. The kills you get outside of the circle don't get you points, anyway.
Speedy
Get ten first! medals
To get a first medal, you need to get the first kill in a game. For this trophy, the first medal can be obtained in any game mode besides co-op. A tip for getting this trophy is knowing that at the start of a game, many people head for the power weapons. Knowing where these power weapons are gives you an advantage and will help you in killing the first enemy that tries to go for it.
I'll Cover You
Get fifty defender medals
To get a defender medal, you have to kill a player that is actively shooting one of your teammates. This is a medal you'll probably get more than one of in most matches and should come without much effort. To improve your chances for these medals, you should be on the move and stay close to teammates.
Fallen Angel
Get fifty afterlife medals
An easy way to get afterlife medals is to throw grenades at an enemy that is close to you. If you happen to get close to an enemy, throw a grenade at them and let them kill you.
Not So Fast
Get twenty shut 'em down medals
In order to get a shut 'em down medal, you need to kill an enemy that is on a kill streak (five kills +). There really isn't any tactic you can use other than going for the person on the opposing team with the most kills; they are usually on a streak. Other than that, just let them come naturally.
Jack of All Trades
Get fifteen triple threat medals
To get a triple threat medal you need to get:
- Three kills with long guns (AK47, M4, FAL, etc.)
- Three kills with pistols (92FS, Micro, Pistole, etc.)
- Three kills with explosives (Grenade, RPG, BBQ, etc.)
in the same match. If you're having trouble getting grenade kills, try tossing a grenade at your feet when you're close to an enemy.
You Run, I'll Shoot
Get ten protectorate medals
To get a protectorate medal, you have to shoot and kill 5 enemies that were damaging the treasure carrier. It doesn't matter if the treasure carrier dies. As long as you kill an enemy that has damaged or killed the treasure carrier, the kill will count towards the five kills that is needed for the 'Protectorate' medal. The only mode to get this one is in Plunder.
Back at Ya
Get fifty retaliation medals
To get a retaliation medal, you need to kill the last player that killed you. There are a couple tactics you can use to increase the chance of getting these, but most likely, you will have 50 of these before you even know it.
Kneel Before Z...
Get five put 'em down medals
To get a put 'em down medal, you need to kill an enemy in the knockdown state with your pistol. When an enemy is in knockdown state, they are kneeling on the ground unable to move. An easy way to do this is using the M32-Hammer or a grenade on them, and then finish them off with your pistol.
Rock a Rhyme
Get 100 tricky medals
To get a tricky medal, you have to kill a player with a pistol weapon while hanging.
NOTE: I for one will be more than willing to help anyone out in obtaining the co-op trophies. I'm sure your fellow Cruxis members are willing as well.

You Can't Break Me

Complete all three co-op objective maps on crushing difficulty
The three co-op maps are as follows:
The Sanctuary
The Village
Nepal Warzone
Simply complete all three objective maps on crushing difficulty. You unlock crushing difficulty by completing the map on hard difficulty. Teamwork is key in beating these levels. Stay close to your teammates and make sure to help them out if they've fallen or are being choked by an enemy.
Under Siege

Complete wave ten in one siege game
Siege is probably the easiest co-op game mode. Make sure you stay inside the circle at all times (you'll know all your teammates are in the circle if the flame and perimeter are green) and don't go outside of the circle to get kills. The kills you get outside of the circle don't get you points, anyway.
Speedy

Get ten first! medals
To get a first medal, you need to get the first kill in a game. For this trophy, the first medal can be obtained in any game mode besides co-op. A tip for getting this trophy is knowing that at the start of a game, many people head for the power weapons. Knowing where these power weapons are gives you an advantage and will help you in killing the first enemy that tries to go for it.
I'll Cover You

Get fifty defender medals
To get a defender medal, you have to kill a player that is actively shooting one of your teammates. This is a medal you'll probably get more than one of in most matches and should come without much effort. To improve your chances for these medals, you should be on the move and stay close to teammates.
Fallen Angel

Get fifty afterlife medals
An easy way to get afterlife medals is to throw grenades at an enemy that is close to you. If you happen to get close to an enemy, throw a grenade at them and let them kill you.
Not So Fast

Get twenty shut 'em down medals
In order to get a shut 'em down medal, you need to kill an enemy that is on a kill streak (five kills +). There really isn't any tactic you can use other than going for the person on the opposing team with the most kills; they are usually on a streak. Other than that, just let them come naturally.
Jack of All Trades

Get fifteen triple threat medals
To get a triple threat medal you need to get:
- Three kills with long guns (AK47, M4, FAL, etc.)
- Three kills with pistols (92FS, Micro, Pistole, etc.)
- Three kills with explosives (Grenade, RPG, BBQ, etc.)
in the same match. If you're having trouble getting grenade kills, try tossing a grenade at your feet when you're close to an enemy.
You Run, I'll Shoot

Get ten protectorate medals
To get a protectorate medal, you have to shoot and kill 5 enemies that were damaging the treasure carrier. It doesn't matter if the treasure carrier dies. As long as you kill an enemy that has damaged or killed the treasure carrier, the kill will count towards the five kills that is needed for the 'Protectorate' medal. The only mode to get this one is in Plunder.
Back at Ya

Get fifty retaliation medals
To get a retaliation medal, you need to kill the last player that killed you. There are a couple tactics you can use to increase the chance of getting these, but most likely, you will have 50 of these before you even know it.
Kneel Before Z...

Get five put 'em down medals
To get a put 'em down medal, you need to kill an enemy in the knockdown state with your pistol. When an enemy is in knockdown state, they are kneeling on the ground unable to move. An easy way to do this is using the M32-Hammer or a grenade on them, and then finish them off with your pistol.
Rock a Rhyme

Get 100 tricky medals
To get a tricky medal, you have to kill a player with a pistol weapon while hanging.