1. Mohn returns(one episode lul)
2. Matori plot
3. I think the graduation would probably be in the same episode Ash says his goodbyes?(Cue last minute Vaporeon evolution)
4. Pallet Town and Ash meets Sonia at Oak's, Ash sees Pokemon he's never seen and asks to battle. Ash heads to Galar(I hope they let the lab be a two parter really, first episode is Ash's Alola team meeting and interacting with the Johto-Kalos Pokemon. Next is his introduction to Galar, him saying goodbye to Delia, Oak, Tracey(Wishful thinking here.... *sigh*), and his Pokemon before leaving)
5. Matori doesn't give the TRio **** as she's terrified of Bewear, making up an excuse for them to Giovanni as to why it's not with them. Mimikyu and Mareanie/Toxapex go to Galar with them
Oh yeah, and Rotom Dex is still with Ash lol
You can bet something will happen to Rotom Dex in the first SWSH episode though, instead of something happening to Pikachu like most regions(Got sick, got lost, got his powers stolen, fell off a tower....). Hence his new phone form!
1. Finding Mohn and Magearna becoming active again.
2. I see something happening with Meltan. I could see Matori and her team coming to Alola again to go after all the Meltan and Ash's Meltan evloves into Melmetal to stop Team Rocket. Ash ends up releasing Melmetal so it can be the leader of the Meltan group. (2 part episode)
3. Pokemon School Graduation
4. Ash saying goodbye to his friends and going home and finding out where all his friends are going to go.
5. Team Rocket gives their Alola Pokemon to the boss, Ash back in Pallet Town and learns of Galar and decides to enter the Galar League. Ash and Team Rocket go to Galar
I don't think there will be any Meltan left, with how they keep multiplying it looks like they're going to make 99 before merging with Ash's. A reference to the fact you (stupidly) need 100 Meltan candies in GO. 100 Meltan make Melmetal, and unless Melmetal suddenly becomes this all power oddity, I don't think it needs to leave Ash. It'd be quite amusing to see how Oak gets around feeding the thing on a daily basis! (And answer the most important question, who eats more? Ash's Snorlax or his Melmetal?!)
Literally no reason for it to go. Protecting Alola? *looks at Tapu* That job's taken. Plus if Lillie's allowed to own Magearna, and Mallow catches Shaymin whenever that Gracidea thing happens... only fair Ash is allowed to keep the first legendary he caught.