I think I'm probably in the minority when I say I vastly prefer the originals to Sky. Sky focuses more on plot than the past game, but it doesn't engage me at all. The characters that do matter are either boring (Grovyle, hero) or unlikeable (partner), and the side characters are one-dimensional anime stereotypes. I suppose this is because it's made by the same company that made Danganronpa, that game also has its own plot issues.
Gameplay-wise, there's a lot of things refined, but at the same time, a lot of the challenge is removed, too. IQ skills, an already flawed concept, is made even worse once in this game, as every Pokemon has their own skillsets. This means that some mons get a skillset that breaks the entire game (like being able to see the map or use two regular attacks at once) while other mons get completely shafted. Recruiting Pokemon en masse got easier, but this also gets rid of the difficulty that's a standard with this genre, you don't need to worry about keeping your new teammates alive anymore. The item pouch being bigger is supposed to account for swap shop items and treasures, but even then, you're not likely to fill up 4 whole pages of them. All that extra inventory space makes things convenient, but also gets rid of planning out what items you should bring, use, or scrap in favor of newer, better ones. No anti-savescumming.
In the end, I feel like they strayed away from some dungeon crawler aspects in favor of being more accessible.
