As long as I have been playing Pokemon (started with gen 4), I have always really liked the stories of the Pokemon games, and the inherent potential that came with them. While they captivated me as a child, now that I've gotten older, I have seen the stories as a bit less than what I would now expect from the games. My first, and biggest hope, is that they greatly expand the story of Sun and Moon, making the plot more complex and detailed than those that have come before it. I want deeper characters, richer background info. for the region, the legendaries, the characters, and their motivations. If I could give an one example of what I mean, it would be Pokemon Mystery Dungeon: Explorers of Time, Darkness, and Sky. I absolutely LOVE that game, with all of its richness of story. The characters and the interactions between them are full of emotion and worth giving you attention to, such as Grovyle, Celebi, Dusknoir, Lapras, Dialga, the guild members, even the main character! (Compared to the protagonist of the core Pokemon games, the PMD protagonist is light-years better... because they have a personality and a history!) The main enemy (Dialga) is convincing in his role, bringing the stakes higher, as well as the tension. You have reason to care for the story, is my main point. I want the plot and characters of Sun and Moon to be just as fleshed-out and convincing as the story of PMD, and hopefully GF pulls through.
Another thing I hope GF includes in Sun and Moon is the return of the character customization!! I also really loved this function, giving me the ability to distinguish my trainer/character from the many other players out there, making him his own person. When they took that out from ORAS, I was a bit disappointed, but it was quickly snuffed out with the opportunity to play the one Pokemon generation I had not been able to go through yet. Case in point, I want this to be brought back, and if it is, then they should make the amount of clothing and accessories more expansive.
I have been saying this for a looooong while, and I will continue until it finally happens... but please, make a Dark-type gym!!!!! Dark-type is one of my top three favorite Pokemon types, and for some reason, it has not gotten the privilege of getting its own gym and gym leader yet (seriously, is there a valid reason for this? if there is, can someone tell me, it would be much appreciated.) On the topic of gyms, I want them to really shake up things, like utilize certain environment or battle-based themes instead of simple type-based gyms.