In the Part Shops you can select the Input Zero Codes option to go and use these passwords.
(There is still probably more of these but I haven't found/tested those yet)
Under B-Dabattle, if you press the R button on the character select screen, you may change your current character's costume, for certain characters only.
This is a password you could use when you get the gold pass
Enter these codes at the Parts Shop once you have gained the Bronze Pass. (Note: Each letter set represents the corresponding katakana symbol. Lowercase letters mean the small version of the symbol, and "-" means the long line that represents a held vowel)