For the strongest fleet possible:
- pick Vigilant and Starfaring, pick Dense, Fast and the +Logistics one as traits
- play to endgame and research all the needed techs
- build Hyperion Logistics System on a planet that sponsors your main shipyard (enables you to build small hulls that require only one logistics point)
- make a fleet of 64 ships (IIRC you cannot field more than 64 ships in a battle) that consists of mostly small hulls and some larger hulls to hit your logistics cap
- stack weapons and Zalon Defense Systems (support module that increases attack value and reduces enemy defenses and can be put MULTIPLE times on a single ship), use other support modules if you want
I haven't actually tried it out, but a quick calculation tells me that the resulting fleet could have an attack value in the millions.