What do you think Starlight's special talent is? I'm going to say leadership. She was a mayor and look how she handled the bullies at Fluttershy's flight camp-gently, but firmly which a mark of a good leader.

5135131 Based on it's design, I'd say magic maybe, especially when we also consider the fact that she managed to either create or learn a spell that removes cutie marks, which we've really only seen somepony like Starswirl do something similar