When it comes to kick-ass monster hunting comedy/drama, Supernatural did a full-on Scooby-Doo episode as well.
But with only a handful of episodes left in the series, should Supernatural have managed this crossover? Could they still squeeze one in? Or would seeing Buffy pop up alongside Sam and Dean just be a little too cheesy and unnecessary?
Should: Perfect Pairing
Getting the obvious out of the way, this would simply be an ideal pairing. Both shows deal with monster-hunting, vamp-killing, and saving the world (a lot), and it would be relatively simple to combine them. Seeing Buffy and the Winchesters bump into each other while taking down a nest would be incredible, and there is so much room for comedy in this meeting that it's hard to imagine a way that this wouldn't be truly epic episode.
Shouldn't: Buffy Has Already Been Referenced As Fictional
One of the biggest roadblocks to this kind of crossover is the simple fact that Supernatural has already referenced Buffy as a TV show in the series. In one of the Ghostfacers' episodes, they steel themselves by asking 'WWBD' (what would Buffy do), and in another episode, a character scathingly refers to one of the brothers as 'Buffy'. It wouldn't be impossible to overcome this, of course (the Winchesters themselves are the stars of a fictional series within their series), but it would make things a little more complicated.
Should: Possible Romance
This could actually work as a pro and a con, but there's no denying that if Buffy popped up, there would be a likelihood of one of the boys having a little something with her. Buffy does tend to prefer monsters, but she had her monster-hunter romance with Riley, too!
And there is little doubt that Dean would be blown away by her incredible skills - that's a perfect fling in the making, and one that would be a whole lot of fun to see.
Shouldn't: Buffy Comics Have Already Charted Buffy's Post-Show Future
Obviously, any meeting between the Winchesters and Buffy would have to take place after the end of Buffy The Vampire Slayer - but those years and events have already been chronicled thanks to the Buffy comic book series. If Buffy were to meet Sam and Dean, it would have to either be such a minor meeting that it could arguably not even be mentioned in the comics, or it would mean having to ignore the comic events in favor of a crossover - neither of which are an ideal scenario.
Should: The Supernatural Multiverse Is Already Established
Supernatural has been playing in a multiverse for some time now (and it has even been established that there are multiples of the Winchesters themselves), and this would be an easy way to bring in Buffy & Co, explain away any issues of continuity and timelines, and get rid of them again within an episode. It would also be an interesting way to play with the multiverse when this is such an important plot point in the final season.
Shouldn't: Timeline Issues
This could be dealt with via that handy multiverse, but if the show wanted to go for a straightforward crossover, there would be some serious timeline questions to deal with - primarily, where were each group during the other group's various apocalypses? Dean was born in 1979, in Kansas, and has been part of the hunter business since childhood. Buffy was born in 1981 in LA.
That means that when Buffy was in high school saving the world in the late '90s, Dean would have been a few years older, and a full-fledged hunter. Why wasn't he with his Dad in California, dealing with a Hellmouth? It would seem suspicious that, given their ages, they have never crossed apocalypse-paths.
Should: Better Female Representation In Supernatural
Supernatural is a phenomenal series, but it has been repeatedly criticized for being overwhelmingly white, straight, and male. Buffy (while not faring much better in the racial diversity stakes) was definitely a female-focused series, and it would be fantastic to see even just one more episode where the boys were up alongside a female hunter who is significantly better than them. It may not do much in the long run (and the show has had a few other powerful female characters along for the ride), but it would still be nice to see another female-fronted episode before the end.
Shouldn't: Practical Issues
Storytelling aside, it would be incredibly difficult to bring the cast of Buffy back together to all appear in an episode of Supernatural - not least because many (many) of the actors have already appeared on the show as other characters! Felicia Day, who was one of the Potentials in Buffy, is a main character (Charlie) in Supernatural, Amber Benson was Tara in Buffy and a vampire in Supernatural, and multiple other actors have appeared for episodes here and there. A multiverse/doppelganger explanation could suffice, but it's far from ideal.
Should: One Last Fan Service Episode
At the end of the day, the primary reason that anyone wants to see this crossover in the first place is pure fan service - and that's something that Supernatural does incredibly well. The show is known for getting meta and having some fun with fans, and this would be a perfect opportunity to do that one last time. Some of the best-rated episodes are the ones that get meta, or that reference other shows, and there's no doubt that (practical issues or storyline problems aside), this would be a great one.
Shouldn't: It's Too Late
While a crossover episode would have been a fantastic idea a few seasons ago, Supernatural is currently only a few episodes from a series finale - and that's not the time for fun fan-service episodes like this. The final season has been carefully created to include favorite past characters, references to earlier seasons, and wrap up this incredible show properly - shoehorning a Buffy crossover in there would simply not do either show justice. It could have been great, but at this late stage in the game, it's just not meant to be.
