How many movies have Jeff 'Swampy' Marsh and Martin Olson 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: The O.W.C.A. Files (2015). 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.