How many movies have Bernie Petterson and Kim Roberson collaborated on?

They have worked on 4 movies together! Their first movie together was Phineas and Ferb The Movie: Across the 2nd Dimension (2011) while their highest rated movie together was Phineas and Ferb: Night of the Living Pharmacists (2014). They have not worked together since Phineas and Ferb: The O.W.C.A. Files (2015). They are most known for their animation films together.