All I've got to say about this is that it's 100x more frustrating for the people who are actually in "that one stunt group" than it is for everyone else. They are usually well aware that their teammates are looking at them with that label and much of the time are putting in even more effort than everyone else to try and overcome whatever it is they are struggling with. As a coach, I have found that equal expectations are key to helping this group overcome their struggles. The second you start giving them more credit for doing less than everyone else, or watering down stunts or treating them like "that group," they start to believe that they are indeed not capable of getting to the same level as everyone else. When competition arrives it might be necessary to water something down for one performance in order to succeed, but continuing to work on the stunt at the next practice and truly expecting them to do it usually leads to it clicking at some point.
One thing that drives me crazy is when teammates act like a struggling stunt group is the result of lower skill or ability at the individual level. The athletes in this group are rarely less skilled than their teammates as individuals. Creating several groups that successfully work together is a tough job for coaches. Group dynamics is an intangible thing and a lot of the time it's hard to put your finger on why four (or three, or two...) people work so well together and another four have such a hard time. A struggling stunt group is often the result of something being off in the way they are working together, not a problem with one athlete's talent level. I hate to see kids feeling bad about themselves or thinking they aren't as good as their teammates just because their group isn't finding as much success.