Some of my favourite games are from Pokémon, but from the Mystery Dungeon series (they're roguelites: Red Rescue Team and Explorers of Sky).
Another title that doesn't get much attention (but is very fun) is Pokémon Conquest. The ending is a bit weak in my opinion, but the overall experience is great; I hoped they would do more like this, but they haven't.
Apart from that, I enjoyed the "Izuna: Legend of the Unemployed Ninja" games a long time ago, although I don't like some mechanics & aspects of it, it could be better, but still cool. There's also a method I found to massively grind levels.
"Dragon Quest IX" for the DS is also good in my opinion, I enjoy its vibes, but by some point it's what they call a grindfest, it also has a "reincarnation" system that I generally don't like. If you don't mind spending some time in a game, enjoying its atmosphere, lore, and potential, then this could be one to play, but unless you want to speedrun it, you're going to need some patience.
Some old ones: Robopon. This is super retro and essentially like Pokémon, some people hate it, but others might like it like me, but you can tell it's old. I ended up with a team comprised of a magical granny, a jack-o'-lantern, a toy samurai, and an evil blimp, so you can imagine that there's some cool Robopons in it.
Another that I played some hours but didn't really continue with it: Azure Dreams for the Game Boy Color. This could be a "hidden gem" if you enjoy rogelikes, and retro stuff.
