Rainbow races a mare in the park. She beats her easily, but when the sister cheers that mare up, she rematches. Again and again, the mare loses, and again the filly cheers her onto another challenge until Rainbow lets her win.
The whole affair makes her think about Scootaloo.
You do not put a comma after a question mark unless the question mark is part of a title.
http://www.thepunctuationguide.com/question-mark.html
6322211 Yeah, I got most grammar down, but when it comes to dialogue, I guess it still gets me.