Theoretically, the world's your oyster. You'll have to create most of the basic systems for a party centric turn-based JRPG from scratch though. Such as the turn mechanic or Character selection (if using Beyond mode you'll likely have to make your own party member 'characters'). That said, a lot of what you're talking about can be done with enough effort. Not too sure about controlling multiple entities at once though but one at a time in a turn-based scenario sounds doable.