I just found out about the app from this game. Basically, you raise a foal in the app and can transfer it into the Star Stable MMO once it's reached level 10 and thus, is an adult. Right now I'm raising a Haflinger foal in the app. She's only at level 2, as I've only just gotten her. I chose the paler version (you can chose from 3 coat colors!), as I've always loved palominos of the more pale variety.

There was an option to raise a mustang as well, but I wanted the Haflinger.