Um... the main purpose of a background pony is to be in the background. No dialogue, no impact on the story, they stay in the background as their name suggest. Also, the irony behind your posts is they're actually pretty sexist. Only male royal guards? We have princesses. Stallions don't cry? Go look at this. Stallions don't wear makeup? Well, there's none, but the closest we've gotten in the ways of fashionable is Hoity Toity and Trenderhoof. I'm sorry, but your assumptions are kind of weak.
...but I'm not going to fight fire with fire here, as it isn't my thing. I'm off.