Xenophobic usually takes a bit more to beat.
Usually the crushing victories involve the maxed Ship AI+Admiral with Cautious for range and Kinetic Artillery. They can win with as low as 50-60k if they haven't awakened.
After awakening, things take an odd turn. There seems to be a tipping point in terms of firepower, where even outnumbered, you can crush them, and it's something that doesn't stay in proportion. Their proportionately doomstacked 1vs2 fleet becomes weaker and weaker, the bigger both our doomstacks get, while keeping things 1vs2.
Using Kinetic Artillery+Tachyon Lance, with armor above 80% and rest into shields, Crystal Hulls and Garanthium, things looked like this:
A 50k vs a 100k is a close call.
150k vs ~300k wins handily.
200k vs ~400k was an overwhelming victory, with almost negligible losses.
I suspect we greatly outDPS them with instant damage from Kinetics and Tachyons, while they use Carriers. We get a lead, and the bigger the initial firepower our fleet has, the bigger our lead on them gets before their strike craft get to us.
Cautious looks like the best trait, paired with good, long range weapons. If there's Aggressive and Unyielding, they're also good, and your ships hang around DPS-ing for longer.
Cruisers equipped with nothing but Flak Cannons, charging into their strike craft and mowing down many of them is a very powerful trick for crushing them too, but they seem to come up late. I wonder if there's better anti-Carrier alternatives.