Not sure if it's possible since I don't know how the game handles fleet spawning, but something I'd like to see is restricting faction fleets from using other factions high-end ships. Seeing an Imperium armada or Citadel fleet using bright green Shadowyard fighters just seems... I dunno, out-of-character and silly from an immersion perspective. Particularly when there's a stark contrast in doctrine (e.g., low-tech, heavy, slow Imperium ships using high-tech shield-centric ships).