Item description:

1. Sign and load the save. and Select single player and chose continue. you are in morbid difficulty on the last check point. With.... $9999999999 in cash and 9999 ammo for everything. Including grenades and rocket launcher.
2. First go to the upgrade shop and upgrade the last upgrade left for the rifle. And you will unlock upgrade one weapon to max.
3. Now use rocket launcher and just start blasting away. It is a cake walk. on finish you will get all difficulty based trophies.
4. Now connect a second controller (yes you need it. no other way around it). Select Co-op and local. And continue campaign. Again you are at the last check point of the last level. Walk out with level one and throw 7 or 8 grenades at player 2 and kill her. Now just use your rocket launcher and walk through the level to reach the helicopter. with 9999 ammo for the rocket launcher its a cakewalk again . And you will get both the co-op trophies.

You also get all other one of each trophies like kill so many and such and such etc.

5. Now start a new campaign and on braindead difficulty do a speed run to finish all the level releated trophies.

6. Now same save level select and highest difficulty just speed run the first level.

Now all is left is use youtube to do one level and collect all loot. and ...

and bazinga enjoy your plat.

All the DLC trophies need to be done by themselves as they are event based.