Mostly, the recruiters are located in different regions all around the world, and the map your given shows un-scouted regions of territory where you can fight for your badge.
Those territories though are just chicken pickings.
The most concentrated for these battles will be a new region I'm dubbing as the
This region is located far-far southeast of the jhoto region on a large island containing 3 types of environments. Forest, Mountain and Desert. There is only one town with an established Pokemon center and a small basic mart located on the beach near the forest. However there is no local law enforcement, except for the trainers who guard the town.
The whole island is setup for the battle royale, however when you complete your badge, the finals will not be setup in this region. The location of the finals change every year, like I mentioned in the first post, so its critical to get your badge completed for the winter. Otherwise, surviving in the winter while fighting is going to be more taxing for all the trainers than it will be during the other 3 seasons.