I've found pirates to be extremely easy, at least from the rebel side, due to the fact that they RARELY ever build ANY air defenses. I just bring in a few speeder squads and take down all of the buildings. Then, it's just a matter of mopping up any remaining units. From the imperial side (I haven't really played them since I've been working on a GC on hard setting and the ground games take up quite a bit of time), I'd assume that using bomber strikes would be a slower but equally effective tactic. As a rebel, I've found that going against Imperials is much more difficult, but the ground games are usually turned by the artillery. Without artillery, the Imperial tactic of massing air defenses (at least that's how it plays against me) means that I can't use bomber strikes and I get ground down by the fact that I'm facing 2 or more of each building garrison. Having a screening force out in front to protect the artillery allows me to get into range and take out the ability to resupply with garrisons, though I invariably lose quite a few units (2 or more ATATs, reams of ATSTs, multiple squads of stormies and the like can amass enough firepower to hurt even while I'm taking down the production facilities). I can't really advise on the Imperial side yet, but it would appear that others have given suggestions.