The theorycraft behind building a fleet in GC that can triumph over anything is challenging on it’s own.
There are three goals to build your fleet for: Raiding, attacking and defense. Raiding is purely suicidal, attacking it designed to destroy 90% of the enemy fleet, and defense is to destroy 90% of fleets attacking you.
The strongest fleet, both for attacking and defense, is purely a fighter swarm. I run on the order of 30+ squads of fighters, each a 1.54 speed rebel dual laser fighter. Even with armored anti-fighter cruisers, they can’t hit enough fighters fast enough to prevent lucky shots from eating through their armor, even with 3 repair modules!
Please, give my build a try. What’s more, it lets you capture planets relatively early on. With this build, complimented by 10 Fenrir fast missile cruisers to take out the early bases with slightly larger fleets, you can get up to 5 bases by week 40-50