Ok for all you people who use Co-Op to beat games this is for it.
( Can also be used on 1 Player for spider queen )

        For the spider queen when you first go in, get one person
( on Co-Op ) to go down on the ground. Then the Queen should come
out. When you first jump off the ledge you come from there should
be another ledge below it connected too pipes leading to the first
ledge, the person going down will activate the Queen to come in
then quickly turn around and jump onto the 2nd ledge ( Might take
awhile but it works ) then the Queen will be trying to get you
from the 2nd ledge. The person on the 2nd ledge shouldn't fire
yet, get the person on the first ledge to fire and distract the
Queen then the person on the 2nd ledge will jump down, ( If your
out of ammo there should be some ammo lying on the ground ) make
sure the guy that's up on the 1st ledge has the Queens full
attention before doing this. Get the guy on the ground floor to
get the grenade launcher out, use the incendiary grenades or the
flamethrower too set the queen on fire which should quickly kill
her faster than you both jumping down and trying.

The Caretaker

This is on Co-Op only, First attack the caretaker with the Laser
until he splits in half, that's half the job, get one of the
players to kill the head while avoiding its guns ( Very deadly )
mainly hide behind pillars while its firing. Get the other player
to attack the body so it cant regenerate which then kills the
caretaker fast than you both attacking one of the body parts at a
time.