Watchlists (from our very old Treeline Analytics program) are being replaced by “Collections” in the “new” analytics.

You can learn about Collections here.

Once you have a collection, you can check it out via the Catalog Analysis graph or by using the Analytics view while looking at that collection:

In fact, using that Analytics view, you can check out any list of titles through an Analytics lens, whether a catalog, order, tags, collections, etc.