I just started playing this game a week ago on a friend's recommendation, and OH MY GOD THE FEELS! ;A; I stayed up late every night this week just going through their stories (finished Emi, Hanako, and Shizune, currently trying for Lilly). The stories and characters are so touching, emotional, and thought-provoking. I cried at parts of the stories. I haven't cried in two years, and it felt wonderful!
None of them have cutie marks. And they're all earth ponies. But maybe I'm just stuck on VCR's interpretations (Shizune being a blue pegasus, Rin being a red unicorn, etc.) and can't think of them being anything else.