Anyways, on a more serious note, has there been any work on making an Upgrade Thread? We could compile a list of known information and general arguments.
For Starters
Yugioh has made multiple mentions of containing an infinite multiverse, as collaborated by
DSOD Guidebook Statements "The scene around the beginning of the movie is an image of the multiverse theory, which says that there is an infinite number of universes other than the one we are in, and that there is another you in another universe, and that both these universes and you exist in an infinite number.”"
5Ds Manga Chapter 33 "To Duel is to catch limitless possibilities. In every single instant, a universe is created."
Zexal Manga Chapter 44 "The Astral World and our world float in an ocean of otherworlds."
Go Rush Episode 135, 139, 150 all discuss parallel universes and 150 has Otei absorb parallel universe counterparts of himself.
Similarly, there's also the Duel Spirit World, which is stated by the OCG Stories Manga "Sky Striker" and "Magistus" to contain "infinite" and "endless" worlds. These worlds also have multiple timelines, as seen by the different continuities both Striker, and Magistus and multiple other lore series have. This Duel Spirit World is also treated as the "backside" of the card compared to the Human World's front side.
There's also the argument to be made of multiple sets of infinite multiverses, such as why the Duel Spirit World has different iterations depending on the anime/manga, or why something like Zexal has an entirely different cosmology to DM-GX-5Ds. Duel Links also describes the connection of many multiverses.
So as a benchmark, both the Yugioh Human World and and Duel Spirit World would both be at minimum, 2-A.
Higher Dimensional Arguments
Duel Links: Well this is literally just stated to connect the infinite multiverses and timelines of Yugioh, and is a literal bulkspace, so...
Prana/Afterlife: Both of these are treated as transcendant of Duel Links, with there being an infinite realm of darkness prior to Kaiba ascending into the Afterlife, which is explicitly stated to be "ascending to a higher-level of dimension".
World of Speed: The DB Q&A stated that the World of Speed was stated to transcend space and time and contain its infinite possibilities. I couldn't find citations for this, but this is just a rough draft.
Astral/Barian Realms: The Zexal Manga states that when the "human world connects to the Astral World, they'll reach a higher plane without suffering", a "higher dimension than the world we live in", "the souls of the people there exist on a higher plane than ours", and the Zexal anime, only those with a "Ranked-Up" soul can reach the Astral World. Similarly, the Barian Realm, the cast out form of the Astral World, is stated to be a "meta-energy world" alongside the Astral World in Duel Links and "worlds of high energy" in the anime "with no metaphysics". Rank-Ups also kinda make it blatant that they're treated as a direct superiority and Eliphas's whole shtick is about ascending to a higher plane of existence by "Ranking-Up".
The Barian Realm being the a cast-out version of the Astral Realm, that souls can potentially go to either the Barian Realm, or the Astral Realm if ascended, and the Barian Rank Ups only rank up by 1 rank while the Astral Rank Up ranks up by 2 does suggest a superiority to the Astral Realm compared to the Barian Realm which is superior to the Human World. Although admittedly, Zexal does also imply an equal nature between the Astral and Barian Worlds.
There is an argument that there are instances in which the Human World is implied to be treated as Parallel to the Astral/Barian Realms. We'd need a transcript to determine if the "parallel" is even accurate, but one could see that as either claiming the Astral World/Barian World are parallel to one another, or that the more science-oriented characters were mistaken, especially since initially, Dr. Faker was unable to find a way to access the Barian/Astral Realm prior to sacrificing his friends, and it is only through the usage of energies from the Astral or Barian Realm they're able to travel to said dimensions. Additionally, the Human Realm is treated as inferior, such as when the waves from the Barian/Astral Realm were able to stop time, and the war entirely focused around the Astral/Barian Worlds, while the only instance of the Human World damaging one of these realms was with Hart's powers which explicitly use Chaos. In addition, the part in which the Barian, Astral, Human Worlds were shown as parallel in Episode 142/II Episode 69, it was also explicitly stated the Barian and Human Worlds were still merged, and you can see that it is merged in that duel. Also, only the Astral/Barian Realms were merged at the Zexal finale, the Human World went unmerged and is still treated as generally inaccessible to humans compared to the other way around.
Duel Spirit World
Incidental Random Transcendental Planes:
Mistva is stated be a transcendent entity of whom forces Emva, Hakva and Kaiva to clash to determine who will be his successor, with the winner becoming Mistva and the losers becoming Anva, who would be erased from existence. Mistva even exists in the Extra Deck as reference to existing, in a transcendental zone. The limiting factor here is that Mistva's showings are planetary. But you know, Anva is shattering reality in Ryu-Ge End.
The Lightsworn's Realm of Light is stated to be beyond space and time, have laws separate from the rest of time and space, and that if they ever fall their immortal souls will return to the Realm of Light.
Banishment/Different Dimension: I'm surprised I've literally never seen anyone making the case for this but, you could argue that the Banishment is in fact a bulkspace for the entirety of the Duel Spirit World. We can see that it connects multiple instances of timelines, such as Dai Grepher's two paths on the Paths of Destiny in Different Dimension Encounter, and universes, like how Trance Archfiend (Trans Archfiend in the OCG as reference to literally being transdimensional) intercepting Genex Ally Birdman who went through a Dimensional Fissure. There's also multiple instances of the Different Dimension having multiple swirling portals (some similar to the Yugioh backing) to different universes, other instances of the Banishment suggesting it contains the Duel Spirit Universes such as Chaos Zone or that the Master Guide 2 lore for Aliens directly states the Otherworld that the Aliens breed their cosmic entities in is "not considered part of the Duel World" and looks strikingly like the banishment.
You might be able to make a similar case for the general GY realms and even the hand (by really stretching Hecahands) as transcendental realms given how the ED is treated and the Banishment but ehhhhhhh.
REMEMBER THAT ONE TIME YUBEL SAID 12 DIMENSIONAL UNIVERSES: Only mentioning it, but probably not. You could make the case that they were referred to as "12 Dimensional Universes" which implies the possibility of 12 universes that comprise of 12 Spatial Dimensions, and how Yubel had to summon a monster of each level to conduct her Super Polymerization ritual, and how Zexal treats Rank Ups as ascensions (and Levels just being the non-Xyz equivalent to Ranks) but yeah no. Unless one of the anniversary GX sets changes things there's really no reason to buy this.
Ten Thousand Dragon: You can literally see the cardback spiral he's coming out from, the same spiral that the OCG Stories Anniversary animation had DM and DMG coming into to show the entirety of the OCG Stories world. He's stated to have created the OCG world, and exists in his own higher dimension from it. If you the banishment being a bulkspace for infinite multiverses which themselves can contain higher dimensions within them (not that high of a stretch given that something like Metaphys Executor, Regenesis Birth, Missing Barrows contain multiple universes within themselves), he'd be 7-D. He's also stated to just be a card, so I guess anyone that scales above it could be considered 8-D?
there goes my judai wank
