Let's start with the note on multiplayer modes. Nintendo has added to the FAQ section, "What do you mean by content that is 'unlawful, infringing, or inappropriate'?", to now include "actions that may be considered to impair the gameplay experience in multiplayer modes, such as intentionally disrupting game progress".
The wording is a little confusing there, but the addition basically prevents streaming any 'unfair' multiplayer gameplay — i.e. intentionally quitting to the home screen to disconnect all players.
The section continues to stipulate that "graphic, explicit, harmful, or otherwise offensive content, including statements or actions that may be considered offensive, insulting, obscene or otherwise disturbing to others", now also officially falls under the 'unlawful, infringing, or inappropriate' banner. No surprises there, then.
What happens if you break any of these rules? You might be banned from sharing Nintendo game content in the future: "We reserve the right to object to any content that we believe is unlawful, infringing, inappropriate, or not in line with these Guidelines. We reserve the right to no longer allow the use of Nintendo Game Content in case of such violations". That second sentence is a new addition, making the company's stance even clearer.
According to Automaton, the Japanese version of the guidelines takes a somewhat more hardline approach. The outlet translates "right to object" as "right to take legal action" and there's an additional warning against "posts that violate public order and morals".
The additions aren't that shocking, all things considered. Nintendo has long been quick to clamp down on anything that could be deemed to sully its good name and the multiplayer tweaks make sense to keep things fair and above board.
You can find the updated guidelines on the Nintendo website, or refer to Diffchecker to see the exact word tweaks.
