Kind of a shot in the dark here but could there be multiple gym leaders giving out the same badge? Kind of like how Giovanni had grunts battling for him during Prime, or the Striaton Gym in B/W ect. It might help with the long line issue since some gym leaders are harder to find than others but people still want to battle a specific type of leader. If that makes any sense. Plus it'd be kind of fun to collaborate and brainstorm ideas with another person and opens up the possibility of doing double battles if they wanted.
I remember some people were talking about double battle gym leaders, but being able to split up and do their own thing at the same time would be cool too. Just throwing some ideas out~
Edit:
Derp nevermind there's already a thread for that. : D;;