The Little Giants! Haha, just kidding. By the way, this is a fun topic dew.
Here are a few more fantasy type teams from movies, some were not even shown so you can use your imagination.
Blue Mountain State Goats (Blue Mountain State)
Boston Rebels (The Game Plan)
Adams College Atoms (Revenge of the Nerds)
Eastern State Univeristy Timberwolves (The Program)
Mean Machine (The Longest Yard 1974 team or 2005 film)
Park City Pirates (Lucas)
Rydell High School Rangers (Grease)
Texas State Armadillos (Necessary Roughness)
As for my pick to win it all, T.C. Williams Titans (Remember the Titans), but I would most likely root for T.L. Hannah Yellowjackets (Radio) because it is one of my ultimate favorite movies!