So what your saying is... Pokemon Sun & Moon is the perfect Pokemon Ranger anime adaptation lol. How you described Pokemon Sun & Moon reminds me of the Pokemon Ranger games.
Hard to say, never played the Ranger games.
Basically I think represents any media that thinks the base of what they're continuing on is running out of steam and needs to experiment with new dynamics and scenarios that could potentially be used and refined upon as things go along.
Remember how all the Golden Ages cartoons plotted out. Not much continuity, low on story, but the draw appeal was all the new characters and ideas, and tons of them would experiment with new characters and formulas and dynamics to see what they get future material out of (eg. one Porky Pig cartoon brought in a one shot called Daffy Duck, he was popular so they reused him, refined his character, and tried him in cartoons alongside other stars like Bugs Bunny, Foghorn Leghorn, Speedy Gonzales, etc to see if they made a funny pairing).
I see that same experimentation sometimes in the SM series, bringing in new characters and dynamics and see if they work out. Some reemerge and even breakout (eg. Masked Royal and Incineroar who were introduced for Torracat's development and now get their own episodes) and some don't (eg. the Popplio vs Rowlet dynamic in an early episode that never appeared again, or Sophocles' Charjabug rivals). XY did a bit of this early on (eg. the Evil Malamar, Team Rocket regaining their sinister cred, Froakie's supposed crush on Fennekin) but quickly ditched it as the main plot begun.