I will say as someone who plays a rocket grunt in BB I have yet to face any gym leaders for my promotions. Granted there’s not been much opportunity for it, but she has no badges at the moment. It’s allowed for my character to have a lot more flexibility with her actions in regards to where she is, who she meets, and what info she’s privy to. So don’t be too worried about that, as in my experience it’s been fun regardless.