Yes you can make a clan without permission, you can make a story without permission and you can do other things without permission, except fixing up another person's page. You'll need to ask the user for that.
I haven't been here in forever and I think I need to make some one here the new Admin. So would you like to be the new Admin? Before I can make you the new admin there are some rules. YOu can't let anyone post any art using the blank base art from Warriors Wikia. They get all bitchy about that. I see people are not following the rules on that one already.
Or post the already used ones on this wikia. I see several are already posted you will have to delete the tell the person who posted them about the rules. I was thinking of opening up role plays again on this wikia as well.
Okay we will make the Clans from the Books as the role play Clans. Also there should be a rule that people can't role play the canon characters from the books. I don't want people to get into fights about who plays who. So for role play, it should only be original characters.
As for pictures. People can find real cat photos, as long as they don't have copyrighted or watermarks on them. Or they can draw some themselves or get costum made pictures by people who can make them.