A good strategy is to build a few Hangar Defense platforms and use bombers, since they do more damage and the Pirates' heavy hitters are basically Kodiaks with no shields but more health/ armor (pirate corsairs). Ring the world with defense platforms, this is especailly effective if you are Advent and have the synergy ability, since with this your platforms eat the pirates for breakfast. TEC have the Argonev starbase, which has some heavy hitting close range weaponry, and pirates are stupid and like to charge straight at something, so these are effective. On the Advent side, the Transcenia starbase upgraded with Meteor storm is a good idea for any defense, but especially against pirates since all they have are frigates. I would set pirates to inactive until you learn better how to play the game, since I'm assuming you're newer (forgive me if I'm wrong). One important thing to remember about Pirates is that they get stronger the longer the game goes on if you have them active, and I don't just mean their raids get bigger, their ships and structures actually get more powerful, more health, more damage, etc. Really late game their Gauss Defense Platforms do like 86 damage per shot, which is almost 3 times what the TEC platforms can do. Basically what I'm saying is you wanna take out the pirates as early as you can. A good strategy (provided you have Rebellion, of course) is to send in your Titan to intercept pirate raids/ raid their base, as this is a good way to level it up, and once your titan gets to level 5/6 it can probably take out the pirate base on its own if you use its abilities well.