I'm just putting together a list of tactics the AI could use to increase it's effectiveness in warfare, as well as the counters to those tactics, in hopes that Frogboy might implement them into the AI in some fashion. Feel free to add on to it!

These may often stray into the obvious, but I've never seen the AI do any of them.

*Use of defenders. Especially when there isn't an orbital fleet manager, the AI should be forming those ships into fleets the moment a target comes in range of the planet and hitting them, especially if it's a transport. If there's an orbital fleet manager, they'll be better off holding the enemy back from orbit, but they should still break out to hit transports if they pose a threat (ie, they have enough soldiers to make an impact)
COUNTER: The AI should keep its transports and other vulnerable craft far enough away from the planet that the fastest ship there cannot reach them. Basically, every planet forms a (2x + 1, 2x + 1) square where vulnerable transports shouldn't venture, where x is the speed of the fastest defender.

*Defenders as combat craft. As of Dark Avatar, the difference between a defender and the comparable heavy fighter is about nill, since the AI usually doesn't put engines on their attack ships. It may be a good idea to simply have them treated the same, with them switching rolls as required. Additionally, planet defenders should be the toughest ship the civ is capable of fielding. Using corvettes to defend when your opponent is using dreadnoughts is just filling up slots in orbit.

*Use of scouts in warfare. There are two major ways to do this: stick a tiny hulled scout into a fleet to fill up space (you generally want more logistics for this) or use a cargo hull loaded with sensors and enough engines to stay safe. The latter is generally more effective. Knowledge is power!

*Use of distance in combat craft. If a ship wants to hit a vulnerable target like a transport that is being protected by seperate fleets of warships, when it IS such a vulnerable target, OR you are fighting as or against a super warrior, they should keep x + 1 distance between themselves and the nearby enemy ships, where x is the speed of that ship. With a super warrior, this guarantees first strike or denies it to your opponent. If a super warrior and his victim were to follow this strategy, the one with the faster speed would put the other in perpetual retreat. If they had the same speed, it would be a stalemate.

*Using planets as slingshots. With DA, you can set the exit point of a ship to the other side of a planet. Using a planet to traverse space faster, then, is like adding 2 extra points to your movement for free. This can get nuts if you have two planets with only one square between them, as you can move between them for 0 movement points.

*Alternate ships strategies. Okay, so this isn't a tactic, but it'd be nice if the different empires didn't build their militaries in such a cookie cutter fashion. Why not occasionally have a civ that rushes to large hulls instead of going on weapon and defense research? Or a civ that IGNORES that tech and relies on having fleets of smaller, technically advanced fighter craft? As it is now, they all seem to build all sorts of ships, whenever, which isn't all that interesting. It might not increase their effectiveness to rely on, say, huge fleets of tiny hulls, but it would make their military functionally different, requiring different approaches and adding more flavour to the game. Maybe it could be race dependent, maybe they decide it on a whim... but it'd be nice, anyways.

Anyone else?