RAGE

This one is pretty easy. Load up the first mission, go to settings and change to nightmare.
General Tips:

Take your time, by going slow and luring enemies back, your partner can take them out

Explore every space. There are a TON of RC Cars, grenades, and wingsticks lying around

Hit A at the ammo crate at the start, the match doesnt being with max ammo.

Enemies spawn after you walk into the adjacent room. I ended up running an RC car to where i thought they would spawn from several rooms away, my partner ran closer to make them spawn. After the stairs down on the first level is where i did this, killed the whole room with this trick.

lastly, try to ambush as much as possible, having mostly dead enemies and smaller numbers makes it easier

In my opinion, the easiest level to get this achievement on is the second one - "Season 1: Pilot". I think this level is easier than the first because all the monsters in this level are club-wielding mutants, and weak ones at that. They can all be one shot in the head with the combat shotgun. The only exception to that is the boss at the end, but he actually dies really fast if you use the shotgun and throw wingsticks at him.
In the first level, most of the enemies are armored and have guns, so it's much harder.

As a general tip, don't use your defibrillator unless you have to. You have a limited number of uses on it and it's better to stay incapacitated and wait for your teammate to revive you, if possible. Also, make sure not to neglect the use of bandages in tight situations. They are really life-saving.

I would argue that "Unwanted Guests" (6th mission, set in Wellspring, featuring Olive) is the easiest.

When you emerge from the basement, there are only two enemies. One has a shield, but you have to throw an EMP grenade to take out the generator anyway.

Next, don't leave the entrance to the bar. Stay at the top of the stairs and take out the enemies in the street one by one. Authority Mutants might charge up the stairs (though only one at a time), but with two shooters that shouldn't be a problem.

When everyone in the street is down, you can either head for the garage and garage's office to pick up goodies, or head to the left and up to deal with two enemies who will spawn when you get near the bend.

Take out the generator at the other end of the alley and deal with 3 or so Enforcers. Head down the alley to pick up goodies, including rocket launchers that you will need near the end.

The next generator is in the street and just down some stairs. When you take out the generator, don't leave the alley. The enemies will all be to the left. Handle this the same way as at the entrance to the bar. Take out the enemies one by one and duck back behind the wall whenever you take damage. Watch for Mutants and perhaps a Shield Trooper to approach. You might consider deploying a turret to distract the Mutant when it comes up the stairs.

When the enemies are done, leave the alley and head up the stairs on the right to pick up goodies. Maybe the designers intended for you to fight the previous battle from the second floor of the house, but if you'd done that you'd have to worry about enemies coming up either of the two stair cases.

Head to the other end of the street towards an open doorway on the right. As you get close, two Authority Mutants will scale the wall on your right.

When you step inside the office, an Authority Elite will spawn outside the other doorway. Blast him with the rocket launcher. You might need more than one clip, but I don't think he will step inside the room you are in.

With the Elite down, go to where the Elite was and use an EMP grenade on the generator at the other end of the courtyard. A few Enforcers will be defending it, but I think that the mission ends as soon as you destroy that generator, regardless of the Enforcers.

I also recommend this mission for the achievement where no one is incapacitated. I've done this mission on normal alone without being incapacitated, and on nightmare with two people and only one incapacitation (the Elite has a lot of firepower).

This was not as difficult as i imagined,

I played with a good friend who knows how to think strategically on his feet.

Start up the first mission and change the difficulty.

Take as much time as you need as there is no time limit,
Split supplies evenly, or if you know one person is going to need more bandages than the other split accordingly,

Use cover when its given, replenish your health and things like that.

Dont try and be a hero. Theres no point charging ahead, You will die, then you will either have to waste a difibulator or your team mate will have to revive you which takes time and they risk dying themselves,

Bandages are life savers, dont try and save them USE THEM WHEN YOU NEED THEM.

There are loads of RC cars in the first level, Use them and dont neglect your grenades either, they will be important when you have quite a few enemies in a tight space.

FINALLY, when you come accross ammo caches you MUST stock up, dont try and go without.

Hope these tims were helpful.

:)

I did this split screen with my brother who had never played the game before in his life, we went on nightmare on every single mission but failed, however we went on the second mission which is in that TV Mutant Bash Show, If you just equip your shotgun, find any wingsticks where ever available, if you think you will die pretty fast equip your medikits, Just keep spraying and praying and you will find it is quite easy to get the achievement on this level. Oh and a reminder if you go down on any part of this mission try to avoid "reviving yourself" see if your partner can help you up, so good luck and hope this helps! :)