During gameplay, split all of the Rocos apart in a safe place. After awhile they will start to play with each other, "dogpile" the person singing the chorus, or line up in a line and count to the number of Rocos you have in Japanese.
Select a level at the World Map screen to get to the "Start? Yes / No" prompt. Then, hold L + R to display the password entry prompt and unlock the following cheats by entering the corresponding codes:
CHEAT FUNCTION - CHEAT CODE 10,000 coins - STARSLOCOROCO All the Muimui - ALLCOLORSLOCOROCO Stage select - SLACRLOCOROCO