Hello Brian, I looked through the Sonos Website with regards to the Move speaker. It says it is
“Weather resistant . With an IP56 rating, Move stands up to humidity, rain, snow, dust, salt spray, UV rays, and extreme heat and cold.”
As to stereo pairing, it appears that is possible on Wifi. So you would need Wifi coverage outdoors:
“Can I stereo pair Move? Yes. You can pair two Moves on WiFi for stereo sound.”
Move looks bigger than One. I had two One SL paired for Stereo over Wifi flawlessly. The sound is good for that size. Five is better, but also a lot bigger… I have not heard Move yet…