You can definitely take Pirate planets with
Acclamator IIs and
Dreadnaught IIs. Just make sure you have at least 150% of the space cap limit's worth of them before you move on anything.
Use the
Acclamators as your anti-capitals. Especially when you get the IIs. That's when they become gigantic bombers. You'll definitely lose some of the Pirates have
Imperial-class ships, but they're much more useful than you may think. The trick is to use them in concert. Keep them knit up tightly, and focus fire when needed. And most importantly, take your time. Don't get too anxious or rushed. Advance slowly, and use fighters as scouts to know what's ahead, if necessary.
Use your
Dreadnaughts as your fighter and frigate screen while the
Acclamators do the heavy lifting. The lasers will clean out fighters with ease, and whatever turbolasers they may have will be quite enough to defend yourself from any frigates the Pirates have.
My fleets usually don't have accompanying fighter squadrons; I use whatever fighter garrisons my fleet carries. If I bring anything along, it'll be Skipray Blastboats. 5-10 of those will turn the tide of any number of fighters the enemy might throw at you.
Just to warn you: removing large numbers of Pirate forces will take a toll on gameplay later in your campaign. Even with full Pirate forces, once you cross a certain threshold, Pirate planets become just a nuisance between you and the Rebellion, and not any sort of impediment. With reduced numbers, that threshold will come much sooner.
Edited by Tropical Bob, 17 December 2009 - 07:57 AM.