This.
I'm a former bowler, you get a talented amateur that has a down and in game (like Walter Ray Williams) and put him on oiled lanes that don't hook, conducive to a down and in style, put him up against a big hooking pro, I'll take the amateur every time.
Sure with billiards. I could play a game of 9 ball against the best and sink the 9 on the break. I'm talking more like the match, not a game or point.
I think Tennis for winning the match, at just like average HS level.
theres plenty of sports where average joe or some guy who just didnt make it for whatever reason who just isnt a pro could beat a pro. MMA, Pool, golf, bowling( hell back 2-3 years ago when i was playing a few times a week i would top 210-220 every game) basketball even i got to think a athletic 6'4-8 guy could take a guy like reggie evans, scalabrine and those big stiffs that are barely hanging on rosters
if your talking about the unathletic guy in gym class then no chance in any sport