How does one even fight Star Gods? I know how to deal with shielded tanks and expect Sectopods to be similar if tougher. But the Star Gods themselves? Oh vey.
In my world, they have established an outpost quite early (month 14 or thereabouts), which receives plenty of supply runs. This give me the opportunity to try my hand at them every so often. My ranged weapons appear to be weak, my melee attacks never seem to connect, but worst of all, I can't even see the guys until I've almost walked into them.
My weapons are bound to get better with time, but I have no idea how I'm supposed to deal with their stealthiness.
My general advice would be to forget about using melee against the Star Gods (both Guardians in red cloaks and true SG's in grey cloaks) unless you're using a gal with very high melee (135+) wielding a very high base accuracy weapon, since they have an absurdly high melee dodge. The Guardians have the worst dodge at ~78 with no back penalty, and the true SG's are even more evasive. Spears and two-handed axes can still work since they hit from beyond melee range.
As far as the stealth goes, I have three bits of advice:
1) True SG's have INVIS 5, meaning by default you can only see them from 5 tiles away, but they are the only enemies on the field with that ability. They also have a unique MIND weapon they use with a distinctive projectile that you can use to get an idea of their location.
2) Use Aye-Phones or dogs to track their movements and narrow down on their location, they have a pretty good detection range and can detect enemies flying above you or behind obstacles. Do note that they can't tell you what vertical level a detected enemy is on.
3) Use armours with good SPOT, at least 5, so you can actually see them from a decent distance. SPOT counters INVIS by adding its value to the detection range, so with 5 SPOT you can see SG's from 10 tiles away instead of 5. Some options are BRAINER, CHROMEBACK, ASSASSIN (10 SPOT!), CARBON, STORMCAT or COMBAT PILOT for catgirls and CYBERPUNK for Lokk'naars. Dogs can also work decently, with 4 SPOT and being very expendable.