Monster Party (1989)

Walking home from a baseball game one evening, Mark gazed up at the misty sky. Suddenly, a blazing star plummeted to earth with a blinding light. When Mark regained his sight, a mysterious creature was standing before him. The creature told an eerie tale about his home planet, the Dark World, where evil monsters were terrorizing the helpless population. He was searching the galaxy for a warrior capable of freeing them from their terrible plight. The creature explained that Mark's bat was the perfect weapon for defeating the evil monsters. Mark considered the creature's proposal for a minute, then agreed to undertake the dangerous mission. After all, he thought, it sure beats going to school!