I just have desires.
N to come back in some way, and in general more special legacy trainers in Battle Tree. Steven, Lance, Alder, N, Zinnia, gym leaders, Elite 4, other Champions, you get the idea.
The Gen 7 legends (Ultra Beasts included) not being shiny locked (wishful thinking).
Move tutors including Defog, I'm sure the ones from ORAS will carry over, so no concern about Stealth Rock and stuff.
More Apricorn Balls, the fact you could only get 1 of each in the overworld is bullshit in SM, you were forced to hack (fuck Global Missions).
I don't know, some Alola version of Super Secret Base trainers, get those Blisseys back (even though triple battles are sadly gone).
Lillie better be more finely presented, she was awful in SM, a million times better in the anime. Less Hau, I hate him, worst rival ever.
An overdose of Guzma, he's awesome.
More Kukui battles, he's cool.
OG Professor Oak making an appearance.
Island Scan events through Global Link. You scan a QR code, Island Scan picks it up and it's a special pokemon. It seems like USUM's Island Scans will favor the starters through the generations. I mean special ones, event mons like Victini, unreleased stuff like that alternate form Magearna, Eternal Flower Floette, HA Heatran, HA legends like the creation trio, shiny Arceus, other shiny mythicals (because it's funny you can wonder trade a shiny Meloetta despite it never being released).
I would say kill Rotom-dex but they gave nice buffs to it (I doubt its Z-move feature will carry over to wi-fi battles of any kind or stuff like Battle Tree).