Another to the pile of games I stopped:
Monster Sanctuary.
Not because it sucks though, monster collecting is not really my thing anymore
Interesting Pokémon aspect, FAR deeper than the original, 3vs3 is uncommon, but why not.
Every monster has tons of skills and passives that you can choose and upgrade, plenty of them combine (like say, a passive for an increased regen buff on one monster working with another one that can actually cast it reliably, and the last that will increase the stats of the whole group while buffed, etc etc), there's a pretty hefty gear system with various effects (more or less unique - maybe focusing a bit more on rare and interesting stuff instead of so many chests to find would have been better) and materials to find and grind to upgrade them.
It's quite well done and on the complex side of the genre, it does make monsters feel a bit more unique than usual, despite a relatively limited move pool, as they definitely have certain archetypes that you can choose to build upon.
And in the same way, monsters also give you skills for the metroidvania part of the game, with tons of stuff to find everywhere, on top of the more common unlockables like double jump. Tons of monster skills do the same thing though, but that's maybe not a problem since getting monsters is no guarantee, you need to do good in combat to get monster eggs... being stuck out of some parts by poor RNG wouldn't be fun.
It's not very complex, but serviceable, and the level design does loop around itself, slowly opening with new abilities. better than some definitely.
It might not really be my thing, but it's quite good, and shows a good grasp of both pokémon-likes and metroidvanias, both with a decent twist and competently made.
Now it's not very pretty, monster designs mostly fall flat, movement is a bit jank, and the writing is stiff, but eh. Nice game.