Crypto is your partner Denjuu in the Power version of Mobile Monsters Telefang (Keitai Denjuu Telefang (Japanese: 携帯電獣テレファング, Keitai Denjuu Terefangu) and a main character in the manga. Telefang is a series of video games published by Smilesoft for the Gameboy Color and Gameboy Advanced. It is a pet collecting game where you battle with digital creatures from an alternate world called Denjuu to earn their respect, recruiting them by recieving their phone numbers upon proving your worth in befriending them. https://wiki.telefang.net/Crypto