Q: How old are the ponies?
The ponies' ages were left intentionally undefined. I like to think of them as having maturity levels anywhere between 12 and 18, (but remember that maturity is different than age. You can be a 10-year-old with the maturity of a 15-year-old, and you can be a 35-year-old with the maturity of a 15-year-old.) For story telling purposes, they needed to be able to live independent of parents, but innocent enough for the type of lessons they learn at the end of the episodes. Since horses are full grown around 5-ish, I guess I sort of justified it in my head that they could be childlike young adults. I know this answer is frustrating for some people, but it happens often in cartoons. How old is Bugs Bunny? Mickey Mouse? Sponge Bob? I don't know either.