I don't think those laws apply. I think it falls under fair use, especially since the content people are bringing just by playing competitively is tranformative, and especially if they have commentary at EVO it would make it even more so which would make the stream fall under fair use. If EVO is also nonprofit there is basically nothing Nintendo can do to sue. I'm pretty sure this issue has come time and time again, especially with youtube and monitization, but (hopefully) if EVO isn't monitizing the stream then it shouldn't matter.
What companies like to do a lot of the time is just send out cease and desists even when they don't have legal grounds. It's part of the organizations responsibility to not back down either. Nintendo probably backed down because of the attention they got, knowing they weren't in the right and could have gotten much more backlash than they are going to get already.
A lot of companies recently have been claiming copyright on games because of sound and cutscenes. Reasons being that by streaming, even when no profit is made and the company is not directly being paid for the use, they have the right to take it down or take them to court.
So fair use is all fine and dandy, but in the eyes of the law, nintendo can easily take down a stream/video because of music, it's something that isn't under fair use since while you can argue fair use on a lets play, nintendo owns the rights to any sounds made by the game, it's their copyright and you are illegally streaming it. Fair use is extremely tricky, but nintendo was 100% in the 'right' to shut down a stream. It's their content and they can take you down for it, they are legally backed in that fact. I'm not saying it wasn't stupid in a marketing sense, I'm also not saying they should have stuck to their guns (hell no), but they were 100% justified in whatever actions they would have chosen to take legally, despite any fair use claim you want to try and throw.
I can't think of any copyright or trademark infringement that creates, especially if Evo is streaming the game for free. We aren't selling or making copies of the game, it's just people playing it. Does anyone know why they can do this? Also, how the hell did Evo not figure this out months ago?
Just because you can't think of it doesn't mean it doesn't exist. I'm not an expert on digital copyright law, but I know for a fact that any music or sounds in the game are property of nintendo and streaming it to the masses without approval of the copyright owner is 100% illegal. I'm not sure on any other sort of claims they could make in this sort of case, but they have the legal staff who are experts in copyright law, you're not going to outsmart them. By asking what authority they have isn't the right way to have gone about this, it's about being reasonable and presenting why they shouldn't use their copyright to shut down the show. It's all water under the bridge now, but if this happens again, you're never going to outsmart a multi-billion dollar companies team of copyright lawyers, the correct way is to present reason and state how this as a consumer effects you willingness to further buy any nintendo products.