Im not exactly a higher user but i know the answer.
People like dark typhlosion (~-~Will~-~, trachy and swampert) are mods handpicked by pokemaster for reasons such as they have been at the site a long time, are trust worthy and have lots of points.
Then editors are the third highest rank picked by pokemaster.
Experts are the 4th highest rank you need 6000 points in pokebase, 500 in battle subway and 500 in meta to be an expert, they have privaliges like use users just with editing powers. Mods and Pokemaster can also make any user into an Expert.
So to answer the question it is pokemaster the super administrater of the site who picks the mods and editors.