>>20220056Megaten series: somewhat difficult, but all entries are good games in their own right: with some exceptions it's much less about the mons and much more about the story. Shin Megami Tensei Nocturne is one of the few that actually has mons that level up and in some cases, evolve.
Dragon Quest Monsters: Fun, Heavy focus on breeding - you will have severe difficulty and may in fact be impossible to beat the game using only wild-caught mons. Dragon Quest V is a main DQ game that has mon raising as a core mechanic, though towards the end of the game the human party members are more than sufficient and outclass more than half the available mons.
Digimon: zero consistency gameplay-wise between the games except the 'story' games on the DS. All are grindy as fuck however in one way or another. The console ones are notorious for having the worst loading times on their respective consoles. Some are actually pretty decent though and playing on emulator gets rid of all the loading issues.
Azure Dreams: Mystery dungeon game with a focus on mon collecting, you can have up to two in your party (eventually) but they eventually get hungry and food items are relatively rare in the dungeon compared to most games. Has a town development and dating sim aspect.
Jade Cocoon: Both are good but are completely different games (they occur within the same timeline however and the hero of the first is also the guild leader of the 2nd). The first has your character transform into the mon you capture, which you can fuse with other mons and they actually change body proportions, gain extra limbs and change textures. Jade Cocoon 2 gives you a party of up to 8 and uses a party/stance formation mechanic for combat. It also ditches the visual differences in mon fusion and just has you improve stats and learn moves.
Crystal Monsters: cute time waster, evos are just palette swaps and has buggy as fuck controls. you'll be switching between d-pad and stylus a lot.