Do we ever see him play any sports or just hear about them?

I think we just see him playing catch with Beaver in the front yard, in "Yard Birds," and playing tennis with the tennis pro's girlfriend in season 5.

We see a little more of Beaver. We see him playing football in the Lightning 11 episode (although it could be a stunt double--don't want the star injured!), doing forward rolls and kind-of batting, in the early episode where Judy hits a home run, and attempting to play basketball in the Park League in season 5 (on tomorrow on MeTV).

Also, I think it's unclear what sports Wally lettered in, at Mayfield High. The sports that are mentioned are football, basketball, track, baseball, and maybe swimming.

I would say definitely track, basketball and football. Wally thought he might’ve gotten a scholarship to state for football.

I believe he was also captain of the swimming team. I may be wrong but in Season 6 "All Night Party" his GF Kathy was saying something to her father about it.

I believe he was also captain of the swimming team. I may be wrong but in Season 6 "All Night Party" his GF Kathy was saying something to her father about it.

I just watched that episode last night. She told her dad, football and swimming. He has three letters though, correct?
Maybe it was gymnastics? June would approve of a Kurt Thomas son.

https://www.youtube.com/watch?v=Eh2E6SgDWqI

We know for sure he was also on the track and basketball teams, from references in other episodes.