MMA: Fedor/GSP - One is retired and the other should have 10 years ago (would add Jones who is still fighting but given his 2 or so positive tests....
Bodybuilding: Yates (90s) or Ronnie Coleman (who retired 10+ years ago and can't even walk anymore)
Hockey: Game has changed too much to be able to say: Gretzgy/Crosby and Lindros (people will argue against it but look at his numbers, especially given era he played in)