What sport does Ponyboy excel in?
In this book, Ponyboy is a pretty good track athlete at his high school. I do not know that he is a star, but he is quite good at it. He mentions this a number of times in the book.
One place we see this is in the part where the newspaper has an article about Pony and Johnny rescuing the kids. It talks about their home lives and, in Pony's case, it talks about how he is a good student and a possible future track star. Pony says at this point that he is the youngest kid on the varsity track team.