Pokemon Sun and Pokemon Moon did so much right for the series.
They got rid of pesky HMs, which were always annoying because you couldn't get some of them through Main Story events. I find Ride Pokemon much more suitable.
The Story, Oh, the story.
If a competition between how good the story of the Pokemon games was, Sun and Moon would take 1st. The characters are unique, fun, and deep. I personally thought that Lillie's character arc was deep, and I still view her as one of the best Pokemon characters.
Alolan forms were cool, and they inspired Galarian forms and Paldean forms in later games..
The new Pokemon were great, however Lunala felt too weak with 2 4x weaknesses due to having Psychic-Ghost, one of the worst type combinations. Other than that, Solgaleo was pretty cool and each of the Ultra beasts was unique in their own way.
My final score is 9.9/10. These games changed everything.