Types of Monsters
In "Crystal Monsters," there are nine types of monsters that can be obtained: animal, fire, water, plant, wind, rock, spirit, dark and light. Each type has its own unique attacks and abilities. Specific types are also better suited to defeat another one, for example, light monsters are more effective against dark monsters.
Capturing Monsters
Monsters in the game can be captured using that monster type's Essence Core. These items are used when in combat with wild monsters throughout the game to capture them once you have first weakened them. It is impossible to capture a monster owned by a non-player character trainer, or any of the bosses.
Breeding Monsters
By visiting Clint, a character in Herbage, you can breed two different monsters together to form a new one. You will need one male and one female monster, and both parent monsters will disappear after you breed them. Breeding monsters allows the child to inherit stats and abilities from both parents, making it much stronger than other monsters captured in the wild. Monster breeding can be a quick and effective alternative to capturing monsters in the wild.
Monster Locations
Different monster types are found in specific locations in the game. Animal, plant, spirit and wind monsters, such as Windycrest, can be found in forest areas. Dungeons typically contain dark or spirit monsters like Spirispear. Volcanic areas in the game are home to fire monsters like Rarogi, as well as rock monsters. Areas near the water, or beneath it such as the Underwater Cavern, contain water monsters like Platipeeve. You can find light monsters in the mountains around Destiny Temple, along with rock monsters.
Special Monsters
Some monsters are special -- stronger versions of lesser monsters. These upgraded monsters have the word "Mega" in their name. Most of these monsters are found later in the game in high mountain areas such as the Secret Plateau or in the Swampland. These monsters are more difficult to capture, though they can prove to be much stronger pets than normal monsters.