For pony fans, we probably all know that the very main goal of the CMCs is to gain their very own cutie marks. Each episode they are featured, they almost try everything to gain their cutie marks, which they don't easily get at all.
But I have a few guesses that each CMC has already got a usual talent which they might be close in getting their cutie marks:
Every since Season 4, Sweetie Belle has a Twilight Time with Princess Twilight Sparkle in studying magic. During the previous seasons, we did not see her perform any magic at all. Probably due to being so young to perform them fully yet. Magic can be what she be mostly good at.
We see she's the sporty and active one in the group. Though, she is too young to fly yet, she uses a scooter and yes already knows that a helmet all the time. That's why I said she the sporty filly.
Among the CMCs, Apple Bloom is the most determined. Before she met her other two friends, she already expressed desire to have a cutie mark. Shes been exploring around lately. So I guess maybe adventuring could be here thing.