Using Moto G (Boost Mobile/Verizon) as a Wi-Fi device without rooting
I bought a Boost Mobile Moto G (2013) for the purpose of using it as a WiFi device as well. I have not rooted, so how I keep from having to activate it is I keep it in airplane mode.  I can still turn GPS, WiFi and Bluetooth radios on while still having it in airplane mode, so this works.
It will keep pestering you (once every day or so) to activate, but it will see that you are in airplane mode and can't activate. You click the button and it exits the activation and you can then use the device.