spiral The minimum settings it allowed me to use it with was:
Google Play Services: Phone/SMS (revoked after RCS activated) & Network
Google Services Framewok: Network
You may can get by without the 2 above. I use them for a couple of other apps.
Contacts (probably not needed, but then you have to remember everyone's #.)
Music/Audio (again probably not needed unless you view a video from a text and want audio)
Network - RCS will not work without this on my & my wife's phones.
Notifications - not needed