The much loved feature of having your favorite Pokémon follow you in the overworld was probably planned to be included in Sun and Moon according to recent findings.
The feature, inspired by Yellow and then debuted in Platinum/Diamond/Pearl with the Pokémon Amity Square, was then featured in full in Pokemon Heartgold and Soulsilver. Now, for good reason, fans won't let Gamefreak forget it exists and push for it in every game.
Well, it looks like it was supposed to be in SuMo.
In all fairness here, anyone who saw that absurd trailer yesterday had to have seen these kinds of reactions approaching fast on the horizon; not only did Snorlax wake up to perform a 'Z-Move' titled 'Pulverizing Pancake' (....), but he did the move on the Donald Trump-esque Pokémon, Gumshoos. It didn't stop there though: we had Raichu riding the swell, and we had a reworked Rattata with one badass mustache.
Ah, what a grand day, indeed. We present, Solgaleo and Lunala, the two newest legendaries in the Pokémon universe. Solgaleo (as seen on left in picture above) will star in Pokémon Sun, and Lunala (right) in Pokémon Moon. Both look like they could deal out a massive whooping on lil Popplio. Here's the new trailer which features the legendaries, as well as new gameplay footage, and a look at the new Pokédex:
In Sun and Moon all players will get a Pokédex inhabited by the ghost-like Pokémon Rotom, who can possess/inhabit objects and machinery.
“It does much more than record Pokémon info—it sparkles with its own personality. The Rotom Pokédex shows your current location and your next destination, and it also gives you advice on where to go next, based on the conversations you have with others! It’s likely to be of great help to you in many parts of your adventure.”
Lastly, here's a detailed look at Aloha: the Hawaii-inspired region of Sun and Moon: