I don't think Nintendo quite knows what they are up against.
First of all, this will never work, people will always make porn of their characters because that's just how people are. It also won't work because it's extremely easy to work around their silly copyright laws. Don't want me using your characters? Then I will slightly modify them or only use part of them for my image.
It's also not illegal to make porn of characters, it's just not. Nintendo tried this once before when they tried to stop Super Hornio Brothers. In the end they ended up spending more money buying up the entire production to stop it, but they couldn't legally stop it from being made.
I mean what is Nintendo going to try to do? Police sites in hoping that their non-legal takedown notices will being accepted? Good luck with that, because it's a waste of time and money.