SMT is the obvious one. It’s much more difficult than Pokemon, but the feel is also pretty different. The monsters aren’t friends, they’re tools. You don’t want to get attached to them and you’ll be replacing them often. If your favorites are weak then you won’t be able to bring them to the endgame without intense autism.
Dragon Quest V is also really good. The human characters are typically better from my experience, but there’s a ton of monsters who have the chance to join your party, and you won’t even be able to have a full human party until the last third of the game. Again, not all of them are viable for use throughout the game, but most will can be used for a good amount of time before they become a liability. The problem with V though is that monsters joining you is entirely up to chance. The last monster you defeat in a random encounter has a set chance of joining you, with many of the good monsters having a 1/64 chance with no way to improve your odds.
