Here's the big warning screen you'll see if you flip through the Online portion of the manual for Super Smash Bros. 3DS, which comes out next Friday in the United States (and is out already in Japan).
It's... strict. As you can see, you'll be penalized on the Nintendo Network for disconnecting from games, idling, etc. You'll be able to report or block other players for similar "bad behavior," the manual says... but if you report too much, you'll be suspended, too. Sakurai's got an IRON FIST.
Expect lots more coverage on the new Smash game in the coming days leading up to launch next week. We'll have a review up next week too.