Puyo Pop Fever Play as Carbuncle
Successfully complete the HaraHara course with either less than four or more than twelve fevers without any continues to unlock Carbuncle. Alternately, successfully complete the game with your number of continues as a multiple of 7.
Play as Popoi
Successfully complete the WakuWaku course on the normal difficulty setting to unlock Popoi.
In-game reset
While playing the game, hold A + B + X + Y and press Start to return to the main menu.
The image featured at the top of this post is ©The Legend of Heroes: Trails of Cold Steel III key art.