Costume for Girl's. Chuggington train Koko engine costume (Small Size 4-6). This Halloween, let your little princess chug through the town as the cutest choo-choo train in this adorable Koko costume that includes a green and purple foam romper (tunic) and matching hat (headpiece). Just like the animated character: Koko, with a handle on each side and eyes. Does not include shirt, pants, or shoes. This is an officially licensed Chuggington kid's costume.