Grim for a Day / Chicken Ball Z / Halls of Time

S2 E4: "Grim For a Day" Billy and Grim trade places for a day to see what it's like in the other one's shoes. "Chicken Ball Z" With the help of a mysterious chicken ball, Mandy enters the local karate championship and takes on all comers. Now, she's out of control, and it's up to Billy to stop her! "Halls of Time" Grim takes Billy and Mandy on a field trip to the Halls of Time, where the past, present, and future are monitored.