Yes, now you can share your android phones battery to another android phone.
in simple you can charge an android device using the OTG cable via another android phone,
How to charge your smartphone using OTG,
So to do it you must have an OTG cable and a Data cable too.
Now lets talk about how to connect or which one will get charged.
so in which phone you connect the OTG cable actually it turns into a Power Bank, and which you connects to Data Cable it will get charged, actually you are transferring your phone's battery to another.
But Your phone should support for OTG by which you are transferring battery, doesn't apply to which getting charged.
so if any of your friend want to charge his phone at where there not any charger is available you can donate some of your android battery to him, or sometimes you can get it too for yours.