This is a new feature in the Mii Fighter book: alternate Miis/costumes. To use them, simply use the Miis included with the chapter (unless it's just a costume), and follow the instructions on the chapter for the original Mii Fighter. Some costume changed may apply.

Rokmutul

Alternate Mii/Costume for Anguirus
Outfit: Mecha Suit

Pterodactyl

Alternate Mii/Costume for Rodan
Outfit: Cybernetic Suit