For Genre Grinder podcast reference.
Finding ways to break down kaiju movies into smaller bits, so I've made one list of all the Toho Godzilla branded movies and this list of movies and monsters that never crossed over with Godzilla. There are a couple of Toho movies here that I don't believe were ever referenced in any of their Godzilla movies.
No King Kong movies, King Kong spin-offs, or other giant Gorilla movies (the Toho Kongs are on the other list). Yetis don't count, shhh.
No super sentai or Ultraman series movies here, either, they'll also get their own lists.