My biggest problem with S/M actually is the... not really perfect online function, to put it in civil words. It's nearly impossible to find someone who wants to do 6v6 battles (I still don't get why Battle plaza is just 3v3...) and IF you do find one it's usually someone who doesn't stand a chance against EV/IV Pokemon - because you can't really see what to expect from others in most cases. Back in XY and ORAS that was way easier - quick look at playtime and won battles in someone's profile and you knew what to expect.
And that Festival Plaza thing is just totally unnecessary.
What I also don't like is that the daycare isn't located on a very open route like usual. That makes breeding even more tedious...
Then of course there's the lack of Trainers for quick leveling - that one guy in the Game Freak house isn't nearly enough.
Then there are no NPCs who can teach your Pokemon special attacks (I'm talking about those guys who are teaching your Pokemon attacks like Knock-Off for BP (is that the right term in English?) in ORAS).
And the lack of most Mega Stones of course was terrible. At least they're slowly letting you obtain them now.
One thing I do like, though, is that the Battle Tree starts with fully evolved Pokemon on your opponent's side. That makes so much more sense.
I aslo liked that S/M was a little more difficult if you didn't use the Exp. Share and didn't grind Exp too much. Still not difficult enough to beat my totally unbalanced playthrough team fair and square, though.
Also sometimes trainers would do... really questionable things. For example: Battle against Lusamine. My Salazzle just got rid off her Clefable and has like 20 HP left. She sends in her Mismagius which gets a speed boost. And then it uses Pain Split.
Full HP Mismagius that could easily have knocked out my 20 HP Salazzle used Pain Split!
That was the most pointless move I ever encountered from an NPC while playing Pokemon...
I still hope that someday there will be a Pokemon game for the older audience. I really have enough of that "10 year old kid gets his first Pokemon, saves the world, destroys evil organizations and becomes best trainer of the country" stuff. It's not just beyond ridiculous, but also also got really old by the fourth time.
Why not have a grown up protagonist? Why not tell a story that doesn't follow the exact same base central theme for once?
And increase the difficulty while you're at it! Elite Four? - Make them the real elite! Totally overleveled when you can first challenge them, full teams, EV/IV Pokemon. Same goes for the gym leaders. Most of the time they're just pushovers whose Pokemon give you slightly more Exp.
Or make gym battles fair - if the gym leader only has three Pokemon, then you too are only allowed to use three.
Totally agree. And while they're at it they could also stop giving trainers Pokemon on levels at which they coul've long since evolved.