> moving 20km to Paste a message is easy and legal

Anything you can do in Ingress apart from actually hacking the players' phones, or sending threats is legal. It doesn't mean it shouldn't be filtered. At some point more than half the lines in the chat were bots trying to sell stuff. Killing either part works - production (farming) or selling.

I'm not saying it's nice and that I support those sellers, but I'd try to kill the root ... and the chat experience always was limited with Ingress. In my local groups it was good enough however to get into contact with people to get then to hangouts or slack or whatever. With Pokemon this is really missing.