TOTALLY COMPLETELY SERIOUS THEORY:
Shelly Team Meteor confirmed. We know she was good friends with Cal, as they both always lived in their brothers shadows, Blake and Bugsy respectively. And when Cal lashed out at her and left, Shelly was devastated. Devastated enough to turn to Team Meteor methinks. When Corey jumps off Beryl Bridge, with Shelly witnessing the aftermath, she was all choked up and traumatized, "because it was Heather's father and she's a young kind." Yea okay, more like she just witnessed her ally kill himself, that'd choke anyone up right? When the Doctor kidnaps her along with the other children, she doesn't seem to resist very hard. She's a gym leader after all, isn't she supposed to be al powerful and stuff? Yet she just gave into their grasp, something that could hint to an alliance... And no, its not because Shelly is a wuss, thats a perfect cover up anyways for it. Nobody suspects the quiet ones. Team Meteor almost immediately locates the kids at Charlotte's manor near Tanzen Mountain, therefore making it seem like there was an inside man among the group... Agent Shelly confirmed. Yea, Shelly attacked Team Meteor alone with you and Cal to protect Heather, but that's all it was, to protect Heather. She wouldn't have cared if it was you or Cal that Blake had captured, only Heather, her one true friend. Shelly knew Corey was a part of Team Meteor from the get-go, and because of that joined to protect him and Heather, as she knew losing Corey would devastate Heather. As Shelly failed in this objective, her only goal was to get Heather back, even if it meant to go against the organization she joined.
As I said before, A TOTALLY LEGIT THEORY AND DEEEEFINITELY NOT A JOKE IN ANYWAY