Elevator Action Deluxe

Go into blue or red doors by pressing , then press as an agent walks by and you will hit him with the door. Do this 50 times and the trophy is yours. If you want to farm just pick a level like 2-4, walk by a bunch of agents and they will follow you. Go into a door and wait for a bunch of agents to walk by the door. You can take a bunch out at one time, although this is another trophy you should be able to get just by playing each level.

There is a counter for this trophy found in the main menu under Agent Dossier. The trophy will pop up after you finish the level.