I would expect this to have been suggested already, and I also saw a very old tweet about it (
), but I didn't see a reference to it in the OP, so allow me to suggest an option to always ignore chat during battle, as opposed to only on a case-by-case basis. I personally find the chat with random strangers to be a bit awkward and I would rather disable it altogether. Especially when some people are outright obnoxious. I'm just a casual player who mostly does random battles on the ladder, so frankly there's not much need or motivation to get to know people, or anything important that needs to be discussed. So there's not much point to it for me. And I know I'm not the only one who would appreciate this feature.
BTW, thanks for the hard work that goes into Showdown, it's amazing.