Welcome to Android Central! You can find plenty of replacement batteries for the G4 on the web (do a search on Google or Amazon) -- it shouldn't matter which exact variant that's listed. But keep in mind that any replacement battery for that phone will probably be almost as old as the phone itself (i.e., about 5 years old), so if it's been sitting around on a shelf for that long, chances are it has also deteriorated somewhat.
I moved this from the Legacy Android forum to the Moto G forum for more specific traffic.