The show repeatedly lampshades the fact MLP ponies are indistinguishable from one another if it wasn't for their cutie marks. We, the audience, never have that problem because the show artists take steps to ensure the main characters are distinct from the background ponies (ie. Rainbow Dash is the only one with a rainbow mane). But if you had to pick out Twilight Sparkle (as a unicorn) in a crowd of 500 purple-ish unicorns, you'd be fucked.
Base +9, tadpolegaming +5, Qwertius +4, Gremrock +5