gmod (and HL2) give massive aim advantages to the rebels. spawn 10 combine a few dozen meters away and have them shoot you. delete them after a few seconds and look at the wall behind you. it'll be peppered with holes and you probably won't have died.
rebels (or civilians) still have a tendency of accidentally teamkilling each other (at least in garrys mod) ((and in my experience with recent npc fights i do)) because one stands behind the other while shooting and basically uses him/her as "cover", but accidentally shoots his/her "cover" and then kills him/her. i pitted combine soldiers with E-11s against rebels with Bowcasters on gm_calamitycoast and only one Combine Soldier died of an accidental teamkill, though none of the rebels decided to hide behind someone (or maybe they did, i don't recall too much)
though, i'd have to do some more npc fights because i tend to forget any npc fight i do
and sometimes combine soldiers have stormtrooper aim with SMGs, coincidence?
edit:
no? gordon could kick a jedis ass with the arsenal he has
I'm gonna kill you in a fight if you say some stuff like this again
luke would probably kill gordon in a fight
while gordon freeman has doomguy syndrome of being able to carry a bunch of weapons with him simultaneously and his feats involving the black mesa incident and the events of half life 2, episode 1 and 2, luke could just slash him with the lightsaber (or just generally do any jedi stuff) and gordon freeman is dead, if luke manages to dodge the bullets and whatnot of gordon's arsenal.
actually, gordon freeman could have a good chance of winning if luke decides to only use his lightsaber and not any jedi magic, because if i recall correctly luke (and basically any jedi) only deflect lasers and not bullets, and if i recall correctly (again) the laser bolts come one at a time after a jedi deflects it (unless if it was on rapid fire, where they slip up and then die because rapid fire lasers), so gordon freeman could just whip out a full-auto gun and just shoot luke to death. luke possibly can't be fast enough to try to deflect (in other words, swing lightsaber at bullets, bullets melt) all the bullets, unless he just force pushes the bullets away in time, but gordon freeman can just recover and keep shooting at luke until he's dead. or gordon could get the super-charged gravity gun (though that was only during the citadel level, and the citadel is pretty much destroyed so he can't get it, so) and just pick up luke and toss him away like a ragdoll
tl;dr: gordon freeman has a good chance of winning against luke because full auto guns solve everything
now, if it was gordon freeman versus darth vader, vader could just force choke gordon freeman and he's dead, bam