To be honest, I don't mind if Mega Evolutions stay, but unless they have severe handicaps or are post-game they suck out the fun of gameplay for me. Let me explain, sure, in competitive battling it helps a lot( since Hyper Training is introduced I can finally actually try competitive battling),but the main problem I had with them from the start was that they are SOOOOOO unbalanced. Taking out the fact that the AI in XY was a 12/225( People actually checked this) and that Junichi Masuda made the game easier on purpose for smartphone kids( I'm not joking when I state this. Just look up the interview) other than some important trainers like the champion or Korrina, NO ONE ELSE USES MEGAS IN-GAME. Like, when I use them, it's fun...for a while...but I just got bored with them afterwards as I just steamrolled through everything. Wouldn't it be cool if in late game you found a youngster with Mega Pidgeot? It would be amazing and actually set a challenge against your Mega! In ORAS/XY nothing stopped you from having a full team with Megastones. Yeah you could only use them once per battle, but if you know what you're doing it's pretty freaking easy to steamroll through everything. Plus you can switch and STILL BE IN the Mega form. It's insane.
I get it, it helps pokemon that were garbage/meh-ish to actual become better, but they need to balance it somehow. As much as I loved to use them, they need some more handicaps.( Like one Mega stone on ONE Pokemon for battle. That's it. Or if not, just make it post-game). I know some people might be turned off by my idea, but damn Megas are way too OP and unfair to some pokemon who are popular coughMewtwocough. I'm actually pretty glad Alola forms exist given that they actually give Pokemon that need it a PERMANENT change to their typing and stats than having it be temporary.