That’s an interesting point. Until this episode, Apple Bloom has usually lead the CMC.
I feel like there may not be a “leader” so much as any of them can take charge if the situation warrants it. Sweetie Belle, as I said, comes across very professionally here. She’s very much doing the part of presenting them as a client focused organization with the experience and skill to help with whatever problem ponies may come to them with.
Sweetie Belle: “You have the CMC guarantee! No matter what it takes, we promise you’ll have our full attention.”
But she also seems aware that there are certain limits to that approach. Take one of the previous season episodes, “The Fault in Our Cutie Marks”. There, we see Sweetie Belle very practically commenting that there may eventually be clients they won’t be able to help.
Sweetie Belle: “Now, Scootaloo, you do know there will always be challenges? Someday, somepony might even come to us with a problem that even we can’t handle.”
So when it comes time to help someone who very likely can’t earn a mark at all, Scootaloo is the one who takes the lead and promises they’ll still try.
Scootaloo: “I know what it’s like to want something that’s out of reach. And just because it hasn’t happened yet doesn’t mean it can’t. Maybe trying for the impossible isn’t so bad.”
It’s not a very professionally minded attitude, but very fitting for Scootaloo personally. She has a soft spot for the impossible dream, and a tremendous amount of hope that with enough work even the impossible might prove achievable.
As for Apple Bloom, she’s a little harder to pin down leadership wise, but I feel like she tends to take charge when the other two are starting to give up. In that sense her leadership style is more a matter of gumption, that no matter how many times something fails, or how close to giving up someone may be, she’ll push onward regardless and encourage others to do so as well. After all, they mainly got their start because of Apple Bloom pointing out how good they were at help other ponies with their marks.