Extend the Overpowerable Logic and make it works towards units.

Tesla Coil has "Overpowerable=Yes" to make it fire a secondary weapon when a warhead with "ElectricAssault=Yes" charges it. This logic can be expanded to make each ElectricAssault support unique for each building, example:

[Warhead]
ElectricAssault.Num=1/2/3...

[TechnoType]
Overpowerable.Num=1/2/3...

This logic can also be changed so that Units and Infantry may also have this feature, not just buildings. The Overpowerable logic works like NoAmmoWeapon, switching to a different weapon when being charged with a warhead with "ElectricAssault=Yes".

[TechnoType]
Overpowerable.Weapon=0/1. This overrides NoAmmoWeapon feature.