I'd imagine any fighting type would excel at sports, especially Machamp and Machoke, as they look like excellent weightlifters. Hawlucha, Hariyama, and Snorlax would be great wrestlers. Hitmonlee would be the ultimate kickboxer! Hitmonchan and Crawbrawler would be good boxers, the list goes on and on!
I think most bipedal pokemon would have an advantage at sports. Although, Jolteon and Electrode would be the best sprinters, given their respective speed stats.
I think Lopunny would be excellent at pole vault/hurdles and perhaps even volleyball, given its thin, agile figure and jumping skills. Lucario as well.
Golduck would indisputably be a fabulous swimmer, given that it states that in its pokedex entry. I'd imagine that Floatzel would be a swift swimmer as well, especially in the rain. (No pun intended.) Greninja would be marvelous as well.
I think Glaceon and Weavile would be magnificent snowboarders.
Kirlia, Gardevoir, and Ralts would be the cutest dancing trio! Gallade, on the other hand, would be a fabulous fencer!
Feraligatr, Charizard, and Blaziken would be incredible basketball players as well, given that they're all fairly tall.
Gorebyss and Dewgong would be legendary divers! (Wailord too, just imagine)
And that's all that I could think of!