Pokémon Association
The Pokémon Association (Japanese: ポケモン協会 Pokémon Association) is a governing body that handles legislature regarding Pokémon. The Association is apparently the group that pays the salary of Gym Leaders, selects them, and organizes Pokémon League competitions across the nation.
They are also apparently responsible for drawing up and often enforcing laws regarding Pokémon, and general competition between Pokémon Trainers. Some of the laws created by the Association include the famous rule which states a trainer can only carry six Pokémon with them at a time.
Their headquarters is in Goldenrod City. The organization has only appeared in the Pokémon Special manga.
It could be said they don't pay well, as most Gym Leaders must work part-time jobs.