I have the recent one (G5), and it has both. 2 Sim card slots, SD card slot, replacable battery. The first one also had a replacable battery. Didn't know the 3rd Generation didn't! In that case I'm glad they reverted their design in that regard.
Oh, seems you convinced me to upgrade again, forgot my phone outside in the rain, it still works but cameras are all foggy and battery is acting weird (loosing 100% in just a couple of idle hours) so time for a new one! Thanks!
The first Moto G (2013) does not have a replaceable battery.
I have one right here.
My bad, remembered it wrong. I mixed it up with the Nexus One I had before that, but that was a high-end phone.