Chief Sherles is the much-overworked police chief of Pyrite Town. Keeping order in such an unruly town would be hard under normal circumstances. The fact that he only has Johnson working under him may mean that the police force in Pyrite Town is even more ineffective than one might initially think.
In Pokémon Colosseum, Sherles is first seen sitting in his police office, where he warns Wes and Rui of the uncontrollable lawlessness in Pyrite and asks that they leave town for their safety. He also appears to investigate the windmill after Silva steals one of the generator's gears and comments on Silva's motives for doing so. Finally, Sherles appears to arrest Evice and Nascour at Realgam Tower during the ending.
Sherles appears in Pokémon XD, but he plays no significant role aside from being a familiar face. After defeating Snattle, however, he reveals news that Cipher's previous boss, Evice, was only a regional boss, hinting at Greevil's position as Cipher's Grand Master.
After defeating Greevil, Sherles can be found outside the Cipher Key Lair, where he is in the act of arresting the remaining Cipher members.
His name is probably a derivative of "Sherlock Holmes", the famous fictional detective.