I know you won't believe me, but I was recently fired from the Gamefreak translation team. I can't prove it, though, so you will need to decide if you believe me or not. I don't care either way. You will see soon.
-Ride Pokemon does indeed replace HMs and there's many more Pokemon to be announced.
-The Chinese starter leaks are indeed correct. Grass/Flying, Water/Fairy, Fire/Dark.
-The Rotom Pokedex will provide a way to keep track of side-quests you can complete within the game. There are a lot of side-quests and jobs to do, as seen in the Pyukumuku trailer.
-Weezing is getting an Ice/Fire Alolan form which is pretty cool.
-There's going to be a new cosplay Pikachu in the game after cosplay Pikachu's popularity in ORAS that will dress up in various outfits worn by past protagonists to celebrate 20 years of the franchise.
-Megas will be in the game. Trust me.
-Ice/Ghost Snowman called Frospirit, Ground type rugby monkey called Gorugrilla, Kittall and Kattsform the normal/various type you've all heard about, Bounsweet's evo the Grass/Fairy Hoppsour, and the all new wild ground/steel pig Tussoil.