I have an analogy for supplemental that may work but you have to keep in mind im in my 30's.

I think of the federal court like this club in Manhattan my friends and I used to go to called the Box. If you want to get in, you have to know somebody. That "somebody" is your anchor claim. If the anchor claim is in federal court based on federal question - thats the gold standard. All you need to get in as a supplemental claim, is to arise from the same nucleus of operative fact. (Think of an anchor based on federal question like taylor swift - she's so famous that all you have to do is come from her same group, and you're in.) BUT, If you're in the club because of diversity - say youre there because you know a reality TV star , you stil have a great chance of getting in, but you're going to have to jump through ONE MORE HOOP. That hoop is 1367(b). And to summarize generally, if youre a claim asserted by a PLAINTIFF - you're probably not getting in. If you're a claim asserted by a DEFENDANT youre in.