Well i know somme of the ennemis in the game, for the rest, see on internet
THe big brown guys launching fireballs: Imps (could be hydras, they both are brown, slow (whitout upgrade) and scary)
The ennemy marines: Zombies (they are equipped with shotguns, can be great ghost/firebat)
Pig guys: Demon (could be a great zergling)
Spiders armed with plasma rifles: Arachnotron (guess wich units... yea, a goon lol)
Big spiders with chaingun (toughter then the other spiders, kinds of boss): spider mastermind (hero goons with 2x more attack)
Zombie with chaingun: Commando (can be a great marine)
Flying ball monster that shots blue n red balls at you: Cacodemon (i really dont know wat it could be, but its a classic monster, dont remove it!)
Fuk'n fat guy with 2 rocket launcher: Mancubus (idk wich unit it could be..)
Skeleton with 2 shoulder-mounted rocket launchers: Revenant (no idea for the unit)
Kind of bull shoting green fire balls: Baron of hell (y not hero hydra?)
Flaming guy that revives others (facultatice) and make you burn, removing 50% of your hp: Arch vile (i once again dont know...)
Cyber demon: the last boss in doom 3 on Xbox, the toughter guy of all pixelized dooms, he kills you in 3 hits with his super fast rocker launcher, but its up to you to find a good unit wich suits to it lol
(for help about wich are the most powerful of ennemies in order, caus they are not in order up here, you go to:)
Here youl know everything and anything bout doomADDITION:
Nvm about i say at 1st, i found a site lol