In order to get this coveted platinum, you must obtain every trophy the game has to offer!
This is no easy feat and will take quite a bit of time, ESPECIALLY on professional difficulty as you will progress to certain points in the levels where you will encounter LOTS of ghosts/monsters and your teammates can be easily downed by enemies…which can be fustrating when you’re trying to dodge both their attacks AND reviving your comrades.
Just use the right weapons for the right enemy and keep reviving your teammates when it is safe to do so….
Good Luck!