This is a recent one, and is the last game I got that I consider I’ve played enough of to be worthy of a place in this years list (that’s why you won’t find Final Fantasy 15 or the last guardian on the list). These games shook up the formula for Pokemon by revamping the challenges your trainer faces, replacing the series staple gyms with the island challenges that require different actions from the players to complete than simply battling, though they do end with a battle against a totem Pokemon, a special version of a certain species that is more powerful than the other Pokemon of the same species. 
The feature that I find the biggest improvement is the addition of “ride Pokemon”. These Pokemon do the jobs of HM moves on the other titles, allowing you to fly, break rocks, swim, and all other things. This is a major benefit as you would end up with a Pokemon in your team who was useless for combat, but had all the moves required for you to get around the world. Now these jobs are all allocated to these ride Pokemon, leaving your entire team open for exactly your team of choice. 
Another interesting feature is that, as well as the usual addition of new Pokemon, there are also new forms of classic Pokemon by the way of “Alolan form” Pokemon. These are special versions of said Pokemon who are unique to this region and have different typing and abilities, examples of which would be Alolan Raichu who is now an electric / psychic type, Alolan geodude and evolutions who are now dual rock and steel type, and even to both Alolan Vulpix and family and Alolan Sandshrew and family, who are now ice type. This is a great addition for old fans to be able to see old Pokemon in new ways. 
The storyline of this Pokemon game has been greatly improved, with more cutscenes, more actual in depth characters, and a little Easter egg that makes the whole story very tragic. 
Finally, while this may sound small, I find it massive. There is the Poke Pellago feature which allows all of your Pokemon that you’re currently not using be put to work on a set of islands that allow them to grow pokebeans, grow berries, hunt for stones and shards, and train up in specific stats or levels. This is great, and it means that all the Pokemon you have in the boxes are actually put to use, and you don’t feel so bad about not using them much. 
This is the biggest shakeup that’s been given to the Pokemon franchise in a long time, and in my opinion it is very well done and makes the best Pokemon release in the series. There are rumours of an enhanced third game coming out to the Nintendo switch, hopefully adding the following Pokemon feature found in the game files as well as more things to do and maybe even more Pokemon, as well as the whole thing being in full HD. We can only hope the rumours turn out as good as they sound. 
Stay tuned for number 9 (sorry I’m running late, I’m really not feeling well at the moment)