How many movies have Hirohiko Yamada and Toshio Takahashi collaborated on?

They have worked on 2 movies together! Their first movie together was Urusei Yatsura: Lum the Forever (1986) while their highest rated movie together was Ranma ½: The Movie — The Battle of Nekonron: The Fight to Break the Rules! (1991). They have not worked together since Ranma ½: The Movie — The Battle of Nekonron: The Fight to Break the Rules! (1991).