In Pokémon, you beat on a monster until it’s weak, then throw a ball to *try* and catch it. Ni no Kuni starts with beating up an enemy like that, but you can’t just choose to catch any monster, they have to first show affection for your team, signaled by hearts over their heads. Then, the game’s leading lady Maru (called “Esther” in the English version) can use her charm ability to bring in the new recruit. There is a timer on this, but when used within the limit, it has 100% accuracy.
Evolution is also different than Pokémon. In Nintendo’s monster catcher, evolution is possible at certain levels, and then the player can choose to evolve them.
Skill learning:
Pokémon – With level, though certain forms of a monster will get skills earlier than other forms.
Ni no Kuni – Some monsters within the same evolution path can’t learn skills that others can, but you can *see* this beforehand, so you can avoid missing something that you think might be useful. You can also see ahead of time what your new stats will be when you evolve.
Levels and Stats:
Pokémon – Monsters maintain the same level when they evolve. Monsters higher on the evolution path tend to learn skills more slowly but have higher stats. You can’t see (as far as I remember) what skills you will and won’t learn or what your stats will be after you do evolve.
Ni no Kuni – Evolving a monster is done with consumable stones found in chests or dropped by enemies, and only after they’ve reached a minimum level. Choosing to evolve a monster will take its level back down to 1, but its base stats will be much better than the Lv. 1 version of its predecessor, and it may have a better growth rate to boot. This means that the Lv. 8 version of some monsters will be superior to the Lv. 18 versions of some others. The higher a monster’s stats at the time of evolution, then in general, the higher its new base is in the new Lv. 1 form. There may also be an impact on the growth rate.
Variety:
Pokémon – Monsters evolve on a straight path (with the exception of Eevee). Pichu can only become Pikachu, and Pikachu can only become Raichu.
Ni no Kuni – Most monsters have only one option for their first evolution, but after that, they can take a different path. You might want to catch a few of certain monsters so that you can explore both paths, because once you evolve up, there is no going backwards (a trait shared by both games).