Here is the full list of all 20 DOOM 2 trophies - there are 5 bronze, 6 silver, 8 gold and 1 platinum.
Beat DOOM 2 in under 2 hours
Beat all the city levels (episodes 12-20)
Beat all the Master Levels
Kill 12 enemies in one shot with the BFG
Beat all the hell levels (episodes 21-30)
Kill one of every enemy
Find all the secret levels
Find a secret level
Beat all the space station levels (episodes 1-11)
Kill 4 enemies in 1 shot with the super shotgun
Get 100 chainsaw kills
Kill yourself and an enemy with your own rocket explosion
Shoot 200 bullets consecutively with the machine gun
Take damage from an environmental hazard
Kill a teammate in co-operative multiplayer
Cause an enemy to kill another enemy
Get 100 kills in deathmatch
Get 25 kills in deathmatch
Unlock all trophies in DOOM 2
Beat every level on Nightmare in co-operative mode