BASEBALL - Rube Waddell (what would modern mental health care and training do for him?)
BASKETBALL - Rick Mahorn, Bill Laimbeer, Anthony Mason (Let's toughen up these kids, shall we?)
FOOTBALL - Deacon Jones, line him up for 60 minutes targeting Brady under 1970s rules.
HOCKEY - Gretzky, duh
RUGBY - Jonah Lomu, second option, Jacques Berger (Youtube these guys)