Honestly, I recommend going back and playing the other games if you want a more challenging experience. Especially Platinum, HeartGold/SoulSilver and Black/White. Black2/White2 are amazing, but I personally prefer the first games. And X/Y is fine (mega evolutions need to come back) but it’s not as great as the previous games. Same for ORAS Imo. Haven’t played Sun/moon or UltraSun/UltraMoon, but I’ve heard very good things about both. Sword/Shield are tons of fun, but I felt them to be easier than previous instalments. And let’s go is definitely to cater to both fans of the main line of games and those brought in by Go. Either way, all pokemon games are great. [spoiler]if you want something more story centric, go play either Pokemon mystery Dungeon Blue/Red rescue team (they remade them on switch) or play Mystery Dungeon explorers of Sky/Time/Darkness[/spoiler]