How many intellectual properties does Nintendo actually own, that this is an issue? Just leave their stuff alone. Refuse to make any videos featuring their first party content, and don't give any views to videos that do.
If it's that big of an issue, cut them out. Make your own stuff. Review and whatever videos of content creators that actually want it. Splatoon is their first successful new IP in how many (decades)? I guarantee that there's some indy and homebrew stuff being made that deserves the youtube coverage more than whatever next-gen Zelda teaser they're running off of now.