The Pixies. They don't get much screentime, but that's probably to their credit. It'll be sad when they buy it.
Anyway, Klan seems to be one of the more thoughtful, intelligent characters in the show. She doesn't throw silly battlecrys and yell at everything in the middle of a battle. She isn't given bad lines. She listens to and observes people. If you asked her a question, she'd give you a straight answer. She also knows how to relax and take advantage of her child-like appearance as a miclone, but only when it's appropiate.
And Nene seems to be a bit unsteady, but it's cute. We only see her combat once where she was shot down by Alto, but she lost in a cute way.
Rere hasn't said a word yet, and the most action we've seen from her is throwing a dart and that was in the last episode.
With any luck, they'll get some unit developement, but Frontier doesn't seem to be going in a direction where that'll happen.