Pause gameplay and select the 'Enter Code' option and input the following codes to unlock the corresponding character.

Ceremonial Robes Nya:
Enter 8755Q9

Garmadon In Pajamas:
Enter LLPQ6X

Highschool Cole:
Enter SMMNCC

Highschool Jay:
Enter XVTULS

Highschool Zane:
Enter 5NHRS5

Mystery Character:
Enter EFZ2XR

Polybag Lloyd (Kendo):
Enter H7HGT3

Sushi Chef:
Enter KU92UG