Answer
The answer is four. Freddie Prinze Jr. and Matthew Lillard collaborated in four films throughout their acting careers. These films include the popular teen rom-com "She's All That" (1999), the horror-comedy "Idle Hands" (1999), the animated comedy "Scooby-Doo" (2002), and its sequel "Scooby-Doo 2: Monsters Unleashed" (2004). These collaborations showcased their on-screen chemistry and acting talent.