Combat carrier AI is funky. Figuring out when to kite with fighters and when to go all-in is hard, so it seems to oscillate between the two. Which is great if you build around it, but problematic if you specialize it too much in either direction. When it works, it's *really* cool though.
LRM/MRM-heavy loadouts that can support from a distance when the AI is operating in the "carrier" mode are a good start.
Officers make a big impact. Long range Gauss builds need that pinpoint accuracy from Gunnery Implants 2 to really shine. A brawling legion can really use armor skill and possibly damage control for free repairs. And aggression/caution let you hint the AI what it should do.
I like brawler loadouts that rely on fighters for a bunch of kinetic damage, and dual Hellbores for flux-efficient armor cracking. The rest of the slots are then flexible - LRMs if your fighters have flares and the officer has the missile speed/tracking skill, a Thumper or two if you want to speed up kills, point defense if the fighters don't screen well enough, etc. The result can hold its own 1v1 against big ships, *and* provide decent support/anchoring for a mixed fleet. Legions are a little weird in that they seem to operate better alone or with a light escort than in a group with other big ships. Other big ships make the AI move it towards the back line, but it's a very good front line ship.
For maximum fun, try an all-ballistic artillery flagship Legion with auxiliary thrusters. Burn Drive has a *really* short cooldown and lets you kite everything as long as you can vent/turn fast enough - get a bunch of combat skills and you can solo the simulator. (This might not be doable in vanilla - it's definitely doable with a few vanilla-friendly mods.)
