Do Custom Tactical SRPG Battle Systems plugins work with this plugin?
Like people could legit make their own Disgaea style game with this if so.
I don't think so. This plugin set should be designed to work in a 3D environment, and from what I've seen, the changes it makes to the classic RPG system wouldn't appear, or would only appear partially, in 3D, making their combined use unfeasible. If the battle takes place in the battle scene, it would work fine, but if the battle takes place on the map tiles, compatibility is not expected.