>>32428222A third alternative to Mega Evolution and Z-Moves. I feel that with three such options, the impact of any one of them stops being a huge issue.
Following pokemon. Yes, it's a meme, but it's a meme I want.
Better Region design with more open ends and out of the way little nooks and crannies. It's fucking 2017. A game company the size of Nintendo can program in basic reactive level progression based on the order you do things. Fuck, I can do that in RPGmaker.
More trainer detail. S&M really bugged me with how disjointedly out-of-place the player character was in the game. A dramatic scene in which life-and-death are on the line, support characters are crapping themselves, and the bad guy is on the rampage? Dead fish stare straight forwards. It made me feel like I wasn't actually part of the action, and was just the manifestation of Lillie's id, out to kill everything then go to sleep mode once there was no more fighting to do. Program in some reactions, maybe have a small personality quiz at the beginning to set which animations go to which reaction flag? I dunno.
Optimize some programming. Seriously. If a game chugs in normal gameplay, I go in to the settings and lower some perimeters. Is it that hard for Game Freak to do the same? I never got into competitive this gen because after my second or third match watching 5 minutes of gameplay stretched out to 8 because of lag, I was fucking done.
Challenge mode. One switch. Increase number of pokemon on a few trainers, improve the AI a tad, EV and IV train important pokemon, maybe skew the odds of status or crits or something. And don't hide it behind a post-game unlock for some godforsaken reason.
More substantial version exclusive lists. There are so many of the fucking things now, there is no reason to not have 50-100 version exclusives in a game. Make playthroughs actually different because of what's available.
Delta Episode-like scenerios in remakes. Way better than finding fug in a cave.