Devastating fleet ships
I've been experimenting with creating the ultimate fleet and I've come up with a pretty good system. First, you need to set up your industry so that you have at least 3 large planets packed with only industry DEA's. set your military spending budget to no less than 20% and turn off the planetary AI on all 3 planets. Always add every new planetary upgrade you come across (i.e. Astro University, etc). This gives you the ability to actually create the ships for your fleet.
Now for the actual ships. First create a Long Range Attack ship in the largest ship hull available. Give it your best armour, shielding, cloaking, ECM, ECCM, sensors, and engines(both system and warp) that you have. Now load it up with your most advanced direct-fire weapons at a heavy or spinal mount. Plasma weapons or beam weapons work best. We'll call this ship a "Sword".
Now create an exact duplicate of the above design except change it's mission to Point Defense and remove all the weaponry. Load it up with point defense beam weapons such as the hard beam, or lightning field generator if possible. If you want, add point defense missiles but it's not necessary. We'll call this ship the "Shield".
Now for your fleets power weapons. Copy the above design and remove all weapons. Select weapon type "Missiles" and choose your most advanced warhead and choose the largest chassi you've got. Create a rack of 5 missiles and give yourself as many 5x racks as you can, adding any armour or shield upgrades you have. Set the ship's mission to Recon and we'll call this happy little fellow "Bow".
Now for the actual fleet. Have one planet mass producing Swords, another Shields, and the other Bows. Create an Armada and put in 10 swords, 6 Shields, and 2 bows. If you do it right you can raise 10 Aramada's worth of these ships fairly quickly, totalling an amazing 180 ships in each combat! The Swords will tear through any ships in range with devastating efficiency, the Shields will provide extensive cover against enemy missiles, while the Bows from each Armada can level even a planet in no time flat. 2 Bows in 10 Aramadas firing 5 missiles is 100 missiles each time they fire, virtually nothing can survive that!