For Battle Backgrounds you also have 3 Options. A User Interface, essentially a RPG Maker Battleback.
Use the Current Map, so the Battle is placed on the Current Map you are on, based on a Battle Focal Point you place.
Or an External Map, similar to Current Map, but it places it on a specific map of your choice.
Now using Current or External Map doesn't really function much differently from using a UI Background, just that it allows you to Use a Map as an actual Background instead.