Battle mechanics need to change in several ways, but the one giant nonsense restriction that has broken balance all over the place single day 1 has been the grouping of weapons into a single salvo per damage type. And of course  it has also made combat carriers the ultimate and uncounterable design.

So change it.

1. Every individual weapon needs to fire independently, rather than per weapon group.

2. To support this, range, accuracy, and fire rate must change from being characteristics of weapon types to statistics of particular weapons.

Bam, fighters instantly balanced (but probably on the weak side), maximized evasion isn't quite so ridiculous, battles will be overall less swingy due to randomness(and therefore the battle predictor will be slightly more accurate), and huge lategame battles will more swiftly and smoothly be resolved.

And it will enable me to make anti-fighter screen weapons, bombers, and carrier-killer cannons, which is nice.