Typically, I define the Weird West genre to be movies that take place in the Wild West and include some supernatural element. This usually means some sort of horror element like vampires or zombies, but that isn't really a requirement. So a movie with cowboys and dinosaurs fits my definition, even though it isn't really what I picture when I think of Weird West.
Yes, it has legendary Ray Harryhausen's stop-motion action, but the whole movie just seems silly to me. I don't know, I guess I'd call this one "Weird West, but I don't care to watch it".
Here's a trailer. I don't think it's streaming anywhere right now though.
I know it's pointless to argue semantics about genre definitions but I do enjoy discussing the boundaries of where one genre ends and another begins.
While I won't argue Valley of Gwangi is Weird West since it has dinosaurs, do you think subverting Western tropes is enough to make something Weird West? I mean, The Quick and The Dead plays pretty loose with the laws of physics just to make for some fun shots:
Or there's Western comedies like Blazing Saddles and Maverick that subvert a lot of Western tropes. I guess I'd almost define Weird West as whether or not something could happen in the West (even though it obviously didn't). So inclusion of vampires, monsters, dinosaurs are "obviously" Weird West but a Western where the "monsters" are simply cannibals isn't Weird West to me. Of course, there's also the sub-genre of Acid Western where things might get super weird but not in a supernatural way. And this is why I like making these posts, to discuss the fringes of the genre.
No, just a subverting of tropes isn't Weird West to me. As I said, it has to be significant. Something that implies much larger implications to the setting/world. Examples: steampunk tech, some alien/scifi tech, magic users, fantasy creatures, etc.
Even better for me is if it feels like a seamless addition. Like if everything about the town is a standard Wild West town but is also a low magic setting where some heirlooms have enchantments or a magic user is uncommon but not strange.