How many movies have Don Lusk and William Hanna collaborated on?

They have worked on 4 movies together! Their first movie together was GoBots: Battle of the Rock Lords (1986) while their highest rated movie together was Scooby-Doo! Meets the Boo Brothers (1987). They have not worked together since Yogi and the Invasion of the Space Bears (1988). They are most known for their animation films together.