Challenge of the Super Friends

When a large and dangerous imaginary friend starts destroying the city, a superhero friend named Imaginary Man comes to save the day, and Mac becomes his biggest fan. When Mac gets recruited as Imaginary Man’s sidekick, however, he ditches Bloo and starts to forget about their friendship. As a result, Bloo joins forces with Nemesis, Imaginary Man’s mortal enemy, to get revenge on Mac.