tough one to nail down to 1, no real surprises...
Football: Rudy, Remember the Titans, The Longest Yard (original), Brians Song (original) 1986 NY Football Giants: Giants Among Men, Draft Day
Baseball: The Natural, Eight Men Out, Bad News Bears
Hockey: Miracle, Slapshot
Basketball: Hoosiers, White Men Cant Jump
Boxing: Rocky
Horse Racing: Seabiscuit
Golf: Caddyshack, Happy Gilmore
Soccer: Victory
somebody mentioned For the Love of the Game, great call. I think its very underrated, even though he pitches* against the Yankees.
*no spoiler, youre welcome.