Since the Kalos times, what matter the most to me are the aesthetics, I've always been into customization and whatnot, so I want more of it. You know, more hairstyle and hair color options (come on, GF, I want anime-esque stuff, if NPCs can have purple hair, why am I bound to use only generic, realistic colors?), clothing variety (geez, they're headquartered in Setagaya, if they're out of clothing ideas, Shibuya is north east from there, it can't be that hard to visit Harajuku for some inspiration (?)), Ball seals (I really liked using the alphabet seals back in G4 :FeelLikeAFiveYearsOld:) and, please, let MC have facial expressions other than o ͜ o
Now, gameplay-wise:
It'd be nice to have some PWT-like facility. I really liked it.
Let us have all the damn berries. If the AI can use custap berries, a non-hacker player should be able to use'em, too.
A stable chaining system. DexNav was a pain to use in areas with a low amount of grass tiles, and SOS battles take forever when it comes to Pokémon you'd actually want to chain.
Bring National Dex back. I was hyped when I saw all previous gen Mons got new entries, and then got disappointed when I found out there was no national Dex. My fav Mon is Pidgeot and I'm mad cuz no new Dex entry.
A better online system. Festival Plaza was awful and GF should be fully aware about the players' opinion by now.
The option to selectively enable or disable animations. I wanna see the move animations, but I definitely don't wanna see item activation, status/weather damage, nor any other end-of-turn animations. They're especially obnoxious in double/triple battles.
A PokéBall-specialized shop that actually sells all kinds of PokéBalls. I'm willing to pay Poké¥100000 for, say, a single Dream Ball. I just want the possibility to have it.
As many of you, I want more mega-evolutions. Or, at the very least, more regional variants. Ever since G6, I've been hoping to see a pegasus Rapidash.
As someone suggested above, a Jurassic Park would be nice. I honestly expexted USUM to have it, since it seemed to fill whatever was incumplete in SM, but alas..
Something I liked from USUM was the many side quests it had. Side quests make in-game worlds feel more natural, and USUM did a neat job at subtly giving us a more mature, somewhat realistic view of something aimed at children. I'd like future games to follow that road.
If some half-naked masked man wants to have a foursome with me and two children, I'd like to be able to refuse (?)
And, I know this is never gonna happen, but I'd like some sort of bond building with certain relevant NPCs. Not like some dating sim, of course, but it'd e nice to have'em say different lines and give you certain items according to how close you're to them.
Yeah, this is merely a whim. I just want an excuse to shipp characters and more yuribait.
Guess that's it.