the fighter zerg works on defense missions, you just might need to throw up a barricade on each direction to distract the enemy fire early on then add a repair turret on each side since they also target ships. but on defense missions, the only downside for me was that eventually i'd have so many ships that the game would slow down. (yes, my computer is crap)
the missions that had the insta-gib ability from opposing race required some barricade spam to block that black void shot when starting right next to them.
final mission - zerg fighters worked on that as well - I didn't even change my armory build since I had no idea what I'd face - I just built interceptors and gunships until threw in a cruiser port (forget name) for the freeze ship, but i lost the cruiser port and a reactor when the annihilator showed up the first time, spammed some barricades to the north then went to startports for the demolisher?. I think I went 2 reactors to start the map, but i don't remember at this point.