As a spec ops, you have the lowest health of all three classes, but you have a advantage, your ability to throw ammo boxes instead of grenades. Also if you get an alternative grenade, if you throw a grenade box, you will automatically get an extra grenade for the alternative grenade. As a spec ops, when you get to a certain level, you unlock the ablility to go invisible, this is handy if there's a bunch of hellfire turrets, but there's too many chimerian soldiers for your team to clear out. Also it's useful if your team gets wiped out and you're left standing, using the invisiblity would allow you to get away safely and to revive a teammate or two without being shot at and killed. Also as mentioned in the Phalanx hint I posted, the Spec Ops' ammo box grenades combined with the Soldier's Wraith Shield makes a formiable mobile shield, if constantly supplying the soldier with the ammo boxes, that will not fail. Also, as a spec ops, you are supplied with, mostly of long ranged weapons such as Marksman or Fareye, these are useful for picking off Steelheads or Ravagers at safe distance.
During the Cooperative play, as a medic, you don't have the most powerful gun at start. But you do have an useful gun, the Phenoix. What you might not realize is that you can use the Phenoix offensively to go in a battle and stay alive even when being shot at. As long you keep a direct laser link from the Phenoix, it will restore your health. Even with the Phenoix's restoration effect, a hit from a Titan will kill you, or maybe critially wound you. But as long you keep moving and keep the laser on an enemy, you will be able to restore the lost health. Only exceptions that you shouldn't do this tactic is with (of course) a Titan, Overseers/Primarchs/etc, a Stalker. It might be possible to pull this off against Maruders. Anyways, the Phenoix also is capable of "stealing" health through the sheilds of the Chimerian Auger or the Ravager's sheild. This is an useful feature as it can distract the Chimera long enough for the soldiers to get around their shields and let her rip. Also, don't forget to heal the other hurt members of your group, you would get a bit of exp. ALSO: Do not, in any circumstances, try to go solo, you might be able to last one on one, or maybe against two or a ravager. But a group of chimeria would kill you easily.
Soldier class, the "Tank Class" people overused it to go forward into battle, with the aid of the Wraith's nifty shield secondary use, making Soldier class capable of standing against a chimerian squad or even a Titan, the setback? Limited charges for the shield. The Medic, or the "Suck and Heal" class, siphons health from chimerians, and uses it to heal other players, even to heal the Medic itself. However, the Medic class has the least offensive power of all three classes. Special Ops, an often misunderstood class, most people think it's good only for ammo refills, since Spec-Ops got low health, making it the "Weakest Link". But if all three classes works together in cooperation. With the Soldier in front, sheild ready, the Spec-Ops behind the Soldier, supplying him with charges/ammo to keep the shield up. And for god's sake, keep the Medic in the back, behind the Spec-Ops, or the Medic will "Leech" off the ammo boxes, resulting in the Soldier's sheild's failure, resulting in the utter defeat. However, keep the Medic in the back for that reason as well so he can heal both the Soldier and Spec-Ops in one shot. This formation is commonly called the "Tank, Ammo, Heal" or simply "The Phalanx".
When facing the Levithan in Resistance 2 you must listen to your fellow man and do what he says but if you still don't undersand then follow my instructions. First wait till he picks you up and when he try's to eat you shoot him in the mouth and you'll have to do this twice as he isn't a weak a stupid hybrid. After this he will place you on top of a building run to the next building quickly. When you have done this find the scafolding and climb in the triangle shaped bridge when done so run across the Levithan will not crush the scafolding bridge but he will damage it so don't get worried.When you have ran across this you will enter a dome shaped building in which you must quickly find the stairs and run down them or jump, then find another set of stairs and run down them. Collect the ammunation for the larrk and then proceed out the window walk along the ledge without falling off. Then out of nowhere the Levithan will garb you shoot him in the mouth when it is open as usual. When you have done this he will fling you into a chimeran tower follow the corridors till you come to a helipad shoot the hybrids. Next you must shoot the Levithan and get his attention for him to go under the brige. Once under fire at the bridge then at him.
If you have had a little problem on the level where you have to overtake a chimeran filled house over the river from a tent where you wake up with the doctor who's trying to stop you from changing into a chimera like "Shepard better known as daedus" you may be getting stuck on the part where you have to kill the big dog like creature well here is what you must. First of all as or after you have succssessfully infiltrated the house find the rocket launcher which is either in the attic or the front right room on the first floor. But when you have found some foot hybrids and some auger hybrids. When you have finished them of without using the rocket launcher, the big dog like creature will come. First go to the first floor andgo onto the balcony find him and shoot one rocket at him. Next run like hell to the other side of the house try not to get caught by the massive electric shockfield thing which covers two thirds of the house and wit for it to vanish and then repeat the process till the chimeran creature is dead.
Throughout the game you may find yourself being killed by a lower breed of hybrid, you know the ones that are weak put come in a group of a hundred but what I found out unfortanately after I'd passed all these parts is that the Magnum is perfect for killing the ugly, screaming, cool to kill hybrids. First of all you should shoot one and only one of the bullet's at the first enemie try and get him as close as possible but no more than two metre's. Then when a group of them starts to come over the body press the secondary trigger and watch the body of the dead hybird explode with fire covering the sorrounding a metre and a half killing the lot of them but don't get to cocky there could be more but now that there's more of them and not just one you have a choice, first you can do what I do which is shoot the closest one quickly and then quickly click the secondrary fire which may I say if not done propally is not going to go that well. Or secondary shoot one then run and lead them back there then click the secondary fire then. Both ways work perfectly well so it's up to your gameplay tactics to decide which way you go and do it. Like a strong suicidal maniac like my approch or like an intelligent person running. It's up to you.