The Pokemon League is far more than a group of pokemon trainers: it is the main body of governance in the country. Each city has its own municipal level of government, but the Pokemon League is the only political organization with nationwide jurisdiction. While most of the League's primary functions involve trainers and their pokemon, they are also involved heavily in the justice and economic systems of Rinjoh.
The Pokemon League mandates registration for all trainers, making certain that they adhere to laws involving the proper use, capture and care of their creatures. Registration allows trainers to access Pokemon Center facilities, as well as enter both city- and nationwide events and tournaments.
The League is deeply integrated into police affairs, specifically those involving the national Rinjoh Police, and since much of the world's economy is dependant upon pokemon, they hold a significant amount of clout in economic affairs due to their sponsorship capabilities.
The Champion is the highest position of power within the League, seconded by the Elite (usually a group of four, sometimes five people). While in some countries the title of Champion is held merely by merit of trainer capacity, the position in Rinjoh requires a variety of other qualifiers, including a minimum age of 25 and a majority vote by the Elite; position on the Elite counsel has similar restrictions.
Each town of sufficient size has a League office called a Gym; each Gym is maintained by a Leader, and has any number of Members, who may or may not have political authority based on their standing and the internal structure of the Gym itself. Regardless of how the Gym is maintained, the Leader will always hold some fashion of political sway within their town. Candidates for Leaders are often selected by the League and then elected on by the town in question.