The Monster Encyclopedia is a book that records all the monsters you've seen and sealed. You can purchase monsters from the Monster Encyclopedia for Coins once you've discovered them. You can also read information about the monsters you've seen, you do not have to catch a monster to view it. When reading information about a monster, the Monster Encyclopedia tells its location, weight, height, and description. Also, when you view a monster, you can press the Details button on the bottom left to view more detailed information about it, like its Mystery Talents, Attacks, and evolutions. The Monster Encyclopedia tells you all about the monsters you've seen and caught!