More Alolan Forms
One of the most impressive features of Sun and Moon are its Alolan forms of older Pokemon. The likes of Vulpix, Rattata, Grimer, and of course, Dugtrio and Exeggutor all see changes to their appearance as a result of being exposed to a different climate. These have been done in such a way that, even if they do look a bit doofy like Dugtrio and its flowing blonde locks, it makes sense why they’ve adopted these new traits, much like real-life evolution.
Unfortunately, there aren’t a ton of Pokemon that have taken on these new forms or made it to the Alola region and as much as we understand more Pokemon mean a bigger file size, it would have been great to see a few more thrown in for good measure. Alolan forms of some fan favorites such as Venusaur, whose back could be massively overgrown from the optimal temperatures of Alola, or Farfetch’d with more exotic coloring and feathers would have still made sense in the context of the world.