*sigh* Two Cruisers can kill a Battleship. Yes, I've tried it.
You can go on about it, but you can't prove more than that you and your friends can't do it. That hardly speaks about the impossibility of the task in general.
Now, I won't talk about the Order Carrier for a moment, because that's a huge beast. Ordinary cruisers can kill a Battleship quite easily. Infernos + Light Mortars + Dodging + Patience = Dead Battleship. You can use Cruiser missiles (aka Cruiser torpedoes) instead of the mortars, your choice. You will have to use Infernos/Mortars against the shield of course. Yes, you will be in range of the Battleship weapons, but at that range you can dodge almost all of its fire. Again, not talking about the Carrier. There are also simple strategies when attacking a large target in pairs, like going full evasive when targetted and attacking when not.
The Carrier may be able to do it somehow, but I admit I'm no expert on that ship.