The reason the old Badges don't count as Ash's Plates.
Before his true form was exposed, Ash couldn't form a connection with the badges in the same way Arceus does with Their Plates.
- And thus, the trials of the old badges — because of Ash being human at the time — isn't a true trial for Ash as an Arceus.
Ash's Dark 'Plate'
While the medal from the Togepi Kingdom is used as his Fairy Plate (to allow him to use the Fairy Type before Kalos), there is only one Dark-Typed Gym in canon — and that's in Galar. It is highly unlikely that Ash will head there just for the badge... But maybe he may get it from Dark City, should the two groups there had figured out what was suggested to them in certain other fics and make a Dark-Typed Gym there.- Another way Ash could get a Dark Type Plate would be as a result of one of the films.
- Both Jossed — turns out, Ash's Dark Plate he gains from a bracelet he gets from Sydney, the Dark-Type Elite 4 Member, after being defeated by Ash.
The past events of Pokémon: Arceus and the Jewel of Life did not happen and neither will they in present time
Simply put, Arceus would've had to be back to the human world, out of his rage-induced slumber, to meet Delia, fall in love with her and conceive Ash, all of which would make Damos' framed betrayal impossible to happen in the past, given how he loved a human enough to conceive a child with her (albeit being aware of it too late). The Jewel of Life would've been given back and everything else would be in order, allowing Arceus to be in peace with humanity for the rest of his life, leading to Ash's birth 10 years before his son begins his Pokemon journey. Ash won't be able to pull off the same scare to Giratina, Dialga and Palkia as he did to Groudon and Kyogre
The Creation Trio strikes Arceus down in his debut movie, showing that regardless of how powerful he may be, they may not feel intimidated by their father as much as the other Legendaries. Ash might have to fight them to get them to stop arguing.- There's a difference between teaming up to stop your father from destroying everything, and teaming up with the sibling you were just fighting with to beat up your father for trying to stop your argument. Also their fight would probably end prematurely anyways as soon as they notice a younger version of their father running around.
- Confirmed. It's Miraidon calling Palkia "Aunt" that snaps them out of their fight, and they're more surprised by Ash's size than by their supposed father's presence when they see him.
Sheena and Kevin will mistake Ash for his father
Unless the author reveals an original prophecy about the Original One having an identical child (not to mention that Ash turning into an Arceus would otherwise warrant as a complete accident), those two will most likely welcome Ash & co. under the assumption he came back to overlook the land of his late friend Damos, before discovering that Arceus now has a child traveling in plain sight. If the time travel elements do happen for some reason...
Ash will finally get to meet his dad in person, and get to know him personally rather than constantly hear legends about him.- Ash might pretend to be his own father to recover the Jewel of Life from Damos (unaware of Marcus' plan) and give it back to its rightful owner, with a near-death experience being the reason why Arceus would be mad at humanity until the heroes fix things.
Similar to the above WMG, Arceus remained absent from his family's life to uphold a Stable Time Loop
If he learns that his future son will come back to the past to save him, and that said son is an Arceus born from a human mother, odds are that he might've left Delia to raise Ash alone out of fear that interfering could jinx things and erase his child (as well as himself) from the timeline. Knowing the existence of time-traveling Pokemons such as Dialga and Celebi, they might've warned him to let Ash grow at his own pace if he wants things to remain as they are (or will be). Manaphy will become the King of the Sea this time around
Given Ash is already the Prince of... well, the Pokemon world, he might not gain anything from another title, and be able to help Manaphy get to the crown without a hitch.- It's not known if Manaphy gains that title, but they do reach Samaya without a hitch... Partly thanks to Kyorge.
Alternatively, the Sea Crown will become another of Ash's 'Plates'
- Jossed.
Manaphy will use Heart Swap on Ash and Jack Walker
Putting aside Jack temporarily becoming a Pokemon god, Ash will have some very awkward (and possibly humorous) time getting reaccustomed to walking in a human body again, even for a short timespan.- Jossed. It was only used on Pikachu and May successfully — when Manaphy tried it on Ash, a barrier on Ash's soul, put in place after the whole King of Pokélantis events, prevented his soul from being swapped.
Serena will not develop any feelings for Ash
He was her childhood crush, and is now a Pokemon god, which might be too much to handle for one teenage girl barely able to figure herself out while starting a journey of her own. She might just drop it believing he's already with Latias (if the latter has developed stronger feelings for him). Alternatively, Serena will become a rival to Latias for Ash's feelings
Being a Pokemon god is not necessarily a deterring reason not to be in love with a human, if Ash's parents are any indication. Serena might decide to do the same as Delia and pursue Ash anyways, with Ash remaining oblivious to any tension, rivalry or potential catfight between any of his love interests. Team Galaxy and Team Flare will capture Ash for their own purposes
If a child of the Original One showing up in Sinnoh and Kalos doesn't raise a few eyebrows, there's nothing preventing Cyrus and Lysandre from trying to catch Ash and force him to recreate the universe in their image.- Team Galaxy might try to use the Red Chain to force Ash to obey them, with him either breaking out or being broken out after a fight with his friends, or worse, his own father coming to the rescue.
- Team Flare's deal is already obvious with Lysandre treating Ash as a messiah of sorts in the battle for Zygarde and the Megalithe. Him being the son of a god is nothing but another reason to spur them on.
Steven will call for Ash's help in curing Chespie
Considering Ash might become more known around the world by the time he gets to Kalos, as well as Steven being aware of his feat of creating Koraidon and Miraidon, he might assume that Ash could use his powers to heal whatever got Chespie in a coma and give him back to Mairin, leading to Lysandre learning more about Ash and plotting to use him... If Ash does get into the Mirror World, numerous things could happen...
- He would meet a crybaby version of himself, ashamed of not living up to their father's legacy, who would remind Main!Ash of the pressure he felt in previous chapters.
- He would meet an evil version of himself, who's abused his Pokemon powers to ravage his world.
- He would meet a completely normal human version of himself, who sounds all too similar to the canon Ash.
- He would meet the other Ashes from Saphroneth's previous stories.
Goh will have a different goal
Given Ash might tell him (or not, as he is quite forgetful) that he not only met Mew but fathered one and might even visit them during their travels, Goh could settle for something else once his first goal has been achieved. Some Legendaries will refuse to recognize Ash as Arceus' son
While Ash may be of the same species as Arceus, he is far much younger and inexperienced. His older siblings might just consider he's not worthy of being treated with the same level of respect and worship as he hasn't achieved as much as their creator yet.- Jossed on Dialga and Palkia's part; they initially mistake him for their father, but on his explaining, easily accept him as their brother.
Squishy/Zygarde (and possibly Z2) will tell Ash about Team Flare's plans sooner
Allying with random humans might've discouraged them from doing it in canon, but Arceus' flesh and blood showing up might just tip the scale and encourage Squishy to confide in Ash so as to stop their evil plans. This won't stop Bonnie from pampering it even after learning the truth sooner. Ash will be able to understand Ultra Beasts
Supposing their dimension was also created by Arceus, Ash might be able to communicate with them and help them get back home sooner. Nebby will get a scarf like Ash's other friends and children
Considering Ash's already made a few, there's nothing that stops him from getting the baby 'mon a gift from Delia. Koraidon and Miraidon will try to act as Nebby's older siblings, as Koraidon already did with Miraidon
Ash-Greninja's Shurikens will resemble Ash's wheels
They might even take a darker color, since Greninja's also a Dark type. Or be gold like his Trainer's rings. Team Plasma will try to kill Ash
It all hinges on the Narrative of Ghetsis, He is more ruthless than Giovanni and more selfish than Lysandre whose goals are at best misguided, at worst destructive.