Why can't anyone make a decent monster collecting/battling game? The closest one to being good that I've played is Cassette Beasts. It shouldn't be this hard.

Monster taming games are kind of my niche (although I'm not particularly interested in playing Palworld). Yo-Kai Watch 3 is the best I've played. Ni No Kuni (the first one, I haven't played the second) is also really good. Those are both big studio games.

Of the indie games I've played, Monster Sanctuary has the best gameplay. The game mechanics are well-designed, rewarding, and very respectful of your time. The main drawback is that the story is not engaging at all. (Also the art style is not super memorable.) The studio that made it has a new game in the works which will be called "Aethermancer" that looks better graphically, if they get a better writer that could be really great.

Nexomon Extinction is another good indie game which is on the exact opposite end of the spectrum. The actual gameplay is somewhat lackluster, but the dialogue and story are fantastic and make the game worthwhile.

You mention Cassette Beasts, that one is solidly in between the other two. The gameplay and the story/dialogue are both pretty good. I feel like it gets the most fanfare out of the three and I have milked a good bit out of the game, but I actually like the other two better in spite of their flaws. The aspects they excel in make them memorable games. Cassette Beasts felt fun enough to kill time and had some innovations, but just didn't make a lasting impression on me.