Here's some basic help for Doom Troopers from Playmates.
The mighty Doom Trooper is heavily armored supersoldier of the Mutant
Chronicles, they usually fight in pairs that are more than powerful
enough to defeat an army of  normal Dark Legionnaire.  Here's some
hints to make your Doom Trooper the Cardinal's favorite and the
terror of the Legion.

You are invulnerable when hanging on a ledge.  This saves your butt
many times in a crossfire.  When things get hectic jump for a ledge.

Save your ammo.  When you hit 0 bullets your gun will regenerate up to
10 bullets.  That won't save you against the bosses.  Against the
legionaires either grab and shoot (which kills them in one shot) or
smash them with your hand to hand attack.  Against bigger foes that's
when you want to exchange gunfire though a couple whacks up close
won't hurt.

Watch out when you shoot a legionnaire, when his head explodes he goes
berserk with his gun when provoked.  When this happens, duck and fire
or leap over the headless chump and beat him up from behind h-to-h.
Your best bet is grab and shoot them.

Remember you can only carry 10 rounds of a special weapon, any other
special weapon you pick up replaces the earlier one, so don't be afraid
to use them.

A grenade does damage to 22% of your life, a sword smack does 15% or so,
while a bullet only does 6%.  If you have to take a hit it's better to
get a wimp shot than a big bomb, so gunning down those grenade throwing
mutants to turn them into pistolshooters is not a bad idea.

The necromutant with the sword does this funny death spasm when shot down
in the air.

The Dark Legion is not immune to getting knocked into lava, having boulders
roll on them and getting blown up by their own grenades

Do not adjust your controls so that you can aim when you jump as you lose
the ability to aim when you are on the ground

Time to get specific.
On Venus, at the Waterfalls of death you must jump on Legion corpses.
There's going to be this long stretch that you must jump to after you
jump on the 2nd corpse.  To get the legionnaire to pop out so that you
can jump on his corpse, jump off the 2nd corpse but control your fall so you
land back on him.  Then gun down the legionaire that pops out and jump on
him.  You are goin to be safe.  Also there's a bonus area in the cave by
the falls

After the Waterfall levels, beware of landmines as they merge well with
the landscape.  Shoot the necromutants with flamethrowers, a special weapon
on occasion doesn't hurt either.  Don't take your time as the enemy
fires missiles at you from the background.

The First boss, Demonognis the apostle of sickness.  This abomination can
only be hurt when he throws bones at you.  Empty all your special weapons
into him as you cannot take specials into the next worlds.  Beware if he
lives to long, he will start drowning you in his puke when it goes over your
head then you'll lose health per second.  If you have no special weapons
you'll have to rely on bullets if you have a nearly empty gun, your done for

The next world avoid touching the beehive structures, they'll jolt you for
damage and scramble your perception so that right is left and etc.

In the aerie stage, just avoid getting hurt too bad and try to map your
way out.

Against Samien or whatever the lord of illusions name is , don't waste
gunfire or specials on him.  His magic makes him immune to those.  Instead
wait he'll launch three attacks.  His first eyebeams, the second is his
staff which creates ground blasts and his third is this whirling ball.
Shoot the ball and it'll spin out of control.  If it hits him he takes
damage.  To avoid getting hurt, occasionally jump for a ledge.

The next stage is Pluto, just avoid falling icicles.  You'll have to
jump into the strong winds to carry you to out of the way areas but
watch that they don't steer you into a sharp ice wall.

In the reactor room, blow up the control panels to get the escape hatch
open.  Blow up all the turbine fans you see as they'll suck you in, killing
you outright.  Go all the way to the bottom right and gun down the masklike
structure that's making the loud noise.  Save your special weapons as you
need them to help you clear a path for a quick getaway, because you have
a minute to escape and when legionnaires pepper you gunfire, it'll be
cutting it close.
When fighting the Razide, note that he is indestructible when  he shoots
so have at him.  He's a piece of cake especially if you have two players.

On the homeworld of the Dark Legion, just avoid getting as much damage
as you can.
Same thing goes for inside the citadel, kill only those who really stand
in your way.
When you go to fight Algeroth, before he teleports in blow up the floating
Legion symbol as it hides a gunclip.  When fighting him, he can only be
hurt with shots to the head.  Use up all remaining specials as he's the
last threat.  If you are lucky, he sometimes ends up teleporting with his
back turned to you as he is mistaken on where you'll be.  When this happens
use it to your advantage as he can only shoot at what's in front of him and
shots to the back of the head are effective.  Avoid his weapons if he's
facing you thought if he uses his machine gun there's no way to avoid all
the bullets so try to avoid as many as you can.  He's almost dead when
his helmet blows up.

Good luck banishing the Legion