Sandbox / Obvious Crossover Method Wick Check

Obvious Crossover Method: Under Tropes Needing TRS due to seeing like it should be YMMV when it currently is not.

Per ATT, all wick (barring sandbox duplicates) have been counted (54/54).

Non-YMMV in source material (5/54)

1. Franchise.Fate Series: The entire concept of Servants means that it's easy to summon a crossover character as a Servant. There are even canonical examples of fictional characters being summoned, so they don't even need to be established as previously existing in the same universe. Likewise, characters from other settings starting their own Grail Wars.
2. Manga.Mazinger Z Versus Transformers: While the Space Bridge is generally a stable method of travel in The Transformers, in the episode "Child's Play" a malfunction sent a group of Transformers to a completely different planet. For this crossover, the lead observer takes advantage of the Space Bridge's explosion to deliberately send the Transformers to Mazinger Z's world.
3. MediaNotes.Jenny Everywhere: Since Jenny is defined by the gimmick that there is a version of her in every reality, it is part of the premise itself that she supposedly already exists in whatever fictional universe you want to write about — just off-screen… And that's before you go into the fact that most versions of Jenny are Dimensional Travelers who can leave their home reality at will to explore.
4. TabletopGame.Infinite Worlds: As mentioned under the Canon Welding entry, the setting itself was basically built to allow crossovers to happen by way of interdimensional travel.
5. VideoGame.Mortal Kombat 11: Kronika's Hourglass, which can bring in characters from other timelines, and is implied to be the explanation for the guest characters' appearances.

Non-YMMV in fan material (12/54)

1. Fusion Fic: Paradoxus: The Setting Merge flavor, to be specific. Azeroth and Magix now happen to exist in the same multi-dimensional universe. It's just they are too far apart that, normally, they would've never interacted at all. Here we have Galadwen and Eudora's constant interdimensional traveling and meddling and Daphne's time travel shenanigans, so things are definitely not normal (more like deranged). Now, there are already some canon points that keep this idea within the realm of possibility: there are elves in both franchises, interdimensional traveling is confirmed and used in both of them, and both of them have entities capable of creating entire dimensions (the First Ones for World of Warcraft and the Great Dragon for Winx Club). Though it's worth noting the Great Dragon is not equal to the First Ones, but to the Titans (like Sargeras), which helps to even out the power scales and avoid a Power Creep, Power Seep scenario and allows for the teaming-up plot this crossover roots from.
2. Tropes in Aggregate: Obvious Crossover Method Notes it's only a trope as a trend in works.
3. Fanfic.A Red Rose In The Blue Wind: The story intersects the paths of both the Sonic and RWBY worlds through the Chaos Emeralds, only this time they work as intended, as opposed to the more common accident plot.
4. Fanfic.Code Prime: In lieu with some traditional Transformers crossover plots, the worlds intersect through a crashed Ark and Nemesis.
5. Fanfic.I Wanna Be The Troll: While trying to figure out what the trollfic will be about, the Author Avatar decides that, since canon IWBTG is already a Massively Multiplayer Crossover, she can use the setting as a vehicle to send The Girl around various canons for funsies. An in-universe/meta example.
6. Fanfic.Mass Foundations: Teleportation Misfire: What kicked off the plot of the fic, adopting a pretty common Obvious Crossover Method, thus making Ethan's motivation to find a way back home, though it was a self-imposed error in improving the Transportalponder and Big Mountain being Big Mountain.
7. Fanfic.Paradoxus: Fusion Fic: The Setting Merge flavor, to be specific. Azeroth and Magix now just happen to exist in the same multi-dimensional universe, it's just they are too far apart that, normally, they would've never interacted at all. Normally. Here we have Galadwen and Eudora's constant interdimensional traveling and meddling and Daphne's time travel shenanigans, so things are definitely not normal (more like deranged). Now, there are already some canon points that keep this idea within the realm of possibility: there are elves in both franchises, interdimensional traveling is confirmed and used in both of them, and both of them have entities capable of creating entire dimensions (the First Ones for World of Warcraft and the Great Dragon for Winx Club). Though it's worth noting the Great Dragon is not equal to the First Ones, but to the Titans (like Sargeras), which helps to even out the power scales and avoid a Power Creep, Power Seep scenario and allows for the teaming-up plot this crossover roots from.
8. Fanfic.Ponyville Goes To The Dragons: Like most FiM cross-over fics, this one starts with Twilight screwing up a spell and teleporting the cross-over characters to her world. In a twist though, the spell was being performed correctly, but what happened was that Applejack ended up startling Twilight just as she was in the middle of casting the spell, causing her to jump and smudge one of the runes used in the spell. (A fact that AJ feels really guilty about.)
9. Fanfic.Xendra: By using the fact characters could choose different outfits for the fateful Halloween when Ethan Rayne turned everyone into their costumes.
10. Pantheon.Gaming Genres N To Z: A plethora of people Sora met across his travels are in the Pantheon, including most if not all of the Princesses of Heart he came across in his adventures. Sora has been renown for his upbeat personality that grants him many friends across many different worlds. As long as you do not mess with him or are doing anything evil in front of him, Sora will extend his hand. His ability to make friends is what may be Sora's greatest asset, as he can connect with people's hearts and draws his power from those connections. That applies to people Sora may have never even met as seen with how his heart repairs a broken Ventus. The Pantheon opens Sora to a plethora of new worlds to explore and gain more connections. Sometimes, this results in Sora landing on their while a conflict he has no context for occurs. People like to point out as the Keybearer, Sora should not meddle in the affairs of other worlds as much as he does but Sora would like to say that it is not his fault he ends up where he goes.
11. Roleplay.Cirque Mystique: The Multiverse and Mutual Masquerade.
12. WebAnimation.Turnabout Storm: Naturally, Twilight messing up a spell causes Phoenix getting pulled to Equestria. The twist is that the "messing up" part is a complete lie. Not only that, but The Stinger in Part 5 implies that Celestia herself was the one who actually messed up the spell, getting the late Mia Fey, who later suggested Phoenix instead.

YMMV (26/54)

1. Common Crossover: Some fandoms are so accessible that they're crossed with just about everything else. Common Crossover has the same issue of if it should be YMMV, putting here as examples isn't about creator intent.
2. Fanfic Tropes: Obvious Crossover Method: A story has an obvious method through which crossovers can occur.
3. FandomSpecificPlot.Animated Films: "Casita creates a door/doors to elsewhere" is proving to be an Obvious Crossover Method.
4. FandomSpecificPlot.Anime And Manga: The show's basic premise, where Louise inadvertently summons a person from another universe during her school's Springtime Summoning Ritual, functions as an Obvious Crossover Method allowing her to summon anyone or anything to replace Saito. Or, alternatively, somehow mess up and send herself to the other universe: be it directly stranding herself in the new setting or being kidnapped/escorted by a resident deity or otherwise powerful entity from that world (usually as retribution for her previous attempts nearly taking someone from their world). In fact, this plot is so common that crossover fics using this framework form the majority of fanfic you'll find for the series in both its Western and Japanese fandoms.
5. FandomSpecificPlot.Harry Potter: "The Late To Hogwarts Fic," in which a young wizard or witch doesn't get their invitation to Hogwarts at age 11, or is unable to go, until later age (usually when romantic plots would be more okay, so from fourth year up) — the other way is to introduce a transfer student (who's usually from the same country/general area and of the same background as the author, and is very similar to them in all aspects, only better). The latter type has the added benefit of 1) making up a new, totally awesome wizarding school 2) enabling the character to have a unique, totally cool wand 3) creating an explanation for unseen-in-Britain, totally super magic 4) allowing the character to have an inherited katana 5) being an Obvious Crossover Method. Details not tying into the character's origins and entrance into Hogwarts usually follow the normal self-insert/wish-fulfillment procedure. This plot was later worked into the video game Hogwarts Legacy, which is only sorta Ascended Fanon since the game itself is considered non-canon.
6. FandomSpecificPlot.Literature: Many fanfics give the main character a different set of powers. This is often used as an Obvious Crossover Method.
7. FandomSpecificPlot.Supernatural: Crossovers with Dark Angel where Jensen Ackles's characters Ben and Alec were cloned from Dean; an Obvious Crossover Method, since Ben and Alec are already genetically engineered twin clones. Frequently with Dean and Sam discovering the twins as children and adopting them, thus fixing the abusive childhoods the twins endured in canon.
8. FandomSpecificPlot.The Owl House: Crossovers with Little Witch Academia are common, due to both shows having a very similar premise (a Muggle with brown hair attends a school for witches and has endless romantic subtext with a green-haired witch prodigy). These stories often has Luna Nova be another school on the Boiling Isles, and Luz and Akko bond over their similar struggles with magic. Wether Akko is a witch or another human in these stories vary, as do the age difference; Either sticking with the idea that the green, blue and red teams are close in age to Luz and her friends (canonically, the teen cast of Little Witch Academia are two years older than Luz), or going with the idea that Akko & co are an older generation, already adults by the time Luz ends up on the boiling isles.
9. FriendlyFandoms.Live Action TV: There's a far amount of crossover between the fandoms for Supernatural and Dark Angel owing to Jensen Ackles (Dean Winchester) having been on the main cast of Dark Angel's second season as Alec McDowell, and Dean and Alec having comparable Lovable Rogue / Handsome Lech personas. It's not uncommon to find crossover fanfics where either Dean and Alec are somehow the same person (despite Supernatural being set at the time it was produced and Dark Angel being 20 Minutes into the Future) or Alec and his psychotic Serial Killer twin Ben, who was also played by Jensen, were cloned from Dean (since the Dark Angel characters are genetically engineered clone brothers in the first place, which makes this an Obvious Crossover Method). Occasionally, you get a non-paranormal AU where Ben and Alec are simply Dean and Sam's younger brothers.
10. Laconic.Obvious Crossover Method: A Fandom-Specific Plot Crossover Opportunity.
11. YMMV.Worm: Fandom-Specific Plot: 99% of all Worm fanfics involve Taylor obtaining a different power than in canon. This also doubles as an Obvious Crossover Method.
12. Sandbox.Loserswithwifi Pantheon Stuff: Louise Françoise le Blanc de la Vallière, God of Popular Setups for Crossover Fanfiction (Obvious Crossover Method)
13. YMMV.Amphibia: In the final episode, Anne is offered the position as Guardian of the Multiverse. While she turns it down, the door is left open for her to accept once she reaches the end of her life, and popular Fanon is that she'll invite Sasha and Marcy to join her, leading to the Fanfic Fuel of the Calamity Trio traversing different universes.
14. YMMV.Dark Angel: Crossovers with Supernatural where Alec somehow became Dean Winchester (which requires a change in the time setting, since Supernatural is set in the present day and Dark Angel is set 20 Minutes into the Future). Or where Dean was the source of Alec and Ben's DNA (which is more plausible).
15. YMMV.Duck Tales 2017: Due to the show featuring several characters becoming superheroes, it's not uncommon with fics that cross over with Paperinik New Adventures (or classic Paperinik) by having the Duck Avenger be an older or even retired hero^note The first Paperinik story was published in 1969, over 20 years before Darkwing Duck who Gizmoduck and/or Darkwing Duck look up to and admire, often with plot revolving around them finding out that Donald is the Duck Avenger.
16. YMMV.Everything Everywhere All At Once: Fanfic Fuel: The basic concept of how dimension-hopping works in this film is an easy avenue for Alternate Universe or crossover fics where a character gains the experiences and skills of another version of themselves, or of a character from another work played by the same actor.
17. YMMV.Final Destination: Take any piece of media with an ensemble of characters. Give one of them a premonition of a horrible accident that kills them all. Have them save the others. Then Death comes for them. Presto, you have the majority of Final Destination crossover fics.
18. YMMV.Five Nights At Freddys: Take one of the many, many works that feature a parody of Chuck E. Cheese's. Now you can do a "Five Nights at X" of that (e.g. Five Nights at Chubby Cheese's, Five Nights at Pete A. Pizza's, Five Nights at Bloaty's, Five Nights at Goofy Goober's, Five Nights at Spunk E. Pigeon's, etc.).
19. YMMV.Gate: Fandom-Specific Plot: What if the Gate opened during a different time period (eg. During World War 1 or 2) or into a different universe?
20. YMMV.Hugtto Pretty Cure: While Pretty Cure crossovers are nothing new, Hugtto does stick out as it's the only Pretty Cure season to actively use Alternate Timelines as a major plot point, while also implying that a greater Multiverse is at play. Not only does the staff use this to justify bringing back every previous team for a special two-parter, but it gives the fans the perfect opportunity to crossover with other franchises as well. After all, what's stopping Chronoa and the Time Patrollers from helping the heroes defeat Crisis Corp...?
21. YMMV.Infinity Train: Fandom-Specific Plot: Crossover fics revolving around transplanting characters from other fictional works and having them traverse the train. After all, it's already from an alternate dimension, so why not jump through several different ones? Given the straightforward requirements for boarding, fans have taken to write crossovers with everything from The Owl House, to Miraculous Ladybug, to even Pokémon: The Series and Over the Garden Wall, as characters from those series board the train to address their trauma and psychological issues.
22. YMMV.Inside Out: Fanfic Fuel: Take every single person, real or fictional, who has ever existed ever in the history of human kind (or even O.C. Stand-in, your own Original Character, or, really, just yourself); what might their versions of the five emotions be like? Doubles as an Obvious Crossover Method.
23. YMMV.Pibby: The short's status as already being a crossover, with the potential for anything connecting to it, alongside the crossover-friendly premise of "the Corruption follows Pibby to a new world and she has to team up with surviving natives to fight it", has resulted in numerous fanart depicting Pibby traveling to almost every piece of fiction people can think of, mainly of the animated kind (whether western cartoon, anime, web animation, etc.).
24. YMMV.Spider Man Far From Home: Fanfic Fuel: The MCU is now part of a multiverse actually after Loki (2021) comes out, as Mysterio's just lying about that, of course), allowing for appearances of characters from the comics, non-MCU Marvel films, Obvious Crossover Method or really anything else you want.
25. YMMV.The Magnus Archives:
    • "Character Y from Fandom X has an encounter with one of the Entities and gives a statement" is a very popular crossover fic format.
    • "[Character or scary thing from other fandom] is an agent of this Entity" also gets a lot of mileage.
    • The final season confirms that alternate universes are a thing, and the finale has the Entities being forced into another universe—and it is possible, assuming they didn't die, that Jon and Martin went with them. Cue loads of speculation about what other fictional world Jon and Martin may have been spat out in, and how that world would cope with the Entities. Night Vale, Hatchetfield, and Gravity Falls have all been touted as possibilities—though, of course, you could also make a case that they ended up in our world.
26. YMMV.The Owl House: Crossover stories with Little Witch Academia frequently has Luna Nova be another school on the Boiling Isles.

YMMV under non-YMMV (5/54)

1. Doppelgänger Crossover: There are several Supernatural and Dark Angel crossover fics. Their ubiquity isn't surprising, as Jensen Ackles's characters in Dark Angel, the twins Ben and Alec, were genetically engineered, and thus could conceivably be clones of Dean from Supernatural as an Obvious Crossover Method. States it's used by fans.
2. ComicBook.Mickey Mouse Comic Universe: In "A Mickey Mystery", Doctor Einmug displays an invention that lets one see what life is like on alternate Earths and later Mickey transfers to one such world. It has been argued that Doctor Einmug should be used if there is a point and not just as a vehicle for gadget, and so far the invention has only been used for a few "Disney-like" worlds. Imagine if the invention was used for other kinds of worlds as well.
3. HarryPotter.Tropes J To R: [Crossover character] raises Harry instead of the Dursleys might be the single most common crossover mechanism for Potter Fanfic.
4. Literature.The Hearts We Sold: The way demons work in this world makes them fit seamlessly into any previously non-magical setting. Now all your favorite characters can trade their body parts away for a wish!
5. Series.Highlander: The concept means a lot of shows can generate crossover fics.

ZCE/unclear/either/other (6/54)

1. Crossover: Obvious Crossover Method: A story has an obvious method through which crossovers can occur. Could go either way.
2. Crossover Relatives: A Sub-Trope to Related in the Adaptation and Obvious Crossover Method.
3. Fandom-Specific Plot: Sailor Earth, Obvious Crossover Method, Fuku Fic, Coffee Shop AU Fic, and The Ship's Motor are subtropes.
4. Sailor Earth: See also: Send in the Clones, Elsewhere Fic, and Fan-Created Offspring. Compare Obvious Crossover Method.
5. Fanfic.Origin Story: At first glance, this story looks like its just a Gender Bender version of the run-of-the-mill standard Buffy YAHF ("Yet Another Halloween Fanfic") plot. Except it really, really isn't. It goes off of those rails almost with the first chapter. Not about the means of crossover.
6. Literature.Revolving Door: With universes that include Real Life, a world 20 Minutes into the Future and just about every other type of past and future beyond, it's exceedingly easy to justify crossovers with other works. Can't tell if in or out of work.

So 17/54 (31%) are non-YMMV while 31/54 (57%) are, so a majority of examples are YMMV. A possible issue is the YMMV overlap with Fanfic Fuel or Fandom-Specific Plot.

A possible fix is to create "Crossover Catalyst" for non-YMMV uses, but that might be redundant with other tropes.