From Bulbapedia, the community-driven Pokémon encyclopedia.
Duking (Japanese: ギンザル Ginzaru) is a very large bodybuilder who lives in Pyrite Town. He isn't quite the mayor of Pyrite Town because he wasn't elected. He's just a very strong man who enforces the law. Luckily for the citizens of the desert town, Duking is actually a kind and fair man who is interested in keeping some semblance of order. He also runs the local Colosseum.
All in all, the citizens fear Duking more than they do the local police force.
Duking does have a soft side. He befriended most of the children of Pyrite Town, letting them work and play in the room hidden behind his bookshelf in his house. He also has a Pokémon that he loves a lot, a pet Plusle.
Miror B. and his Cipher goons had kidnapped Plusle, and held it hostage in Miror B.'s Hideout. Without Duking to stop them, the Cipher grunts went on a crime spree of thievery and extortion in Pyrite Town. Meanwhile, Miror B. began to distribute Shadow Pokémon in Pyrite Colosseum. Only Silva and the kids of Pyrite Town knew the truth about what happened. The other people of Pyrite Town were confused as to why Duking didn't fight against Miror B.'s thugs.
Silva, Duking's best friend, tried to do what he could to stop the spread of Shadow Pokémon and rescue Plusle, but he was unable to accomplish his goals, and was physically hurt in the process. Wes and Rui arrived in the town one day and managed to rescue Plusle and chase away Miror B.
Duking supplies Wes with information throughout much of Pokémon Colosseum, and assists in the arrests of quite a few Cipher members, he even assists Chief Sherles and Officer Johnson in arresting Evice and Nascour after Wes defeated them at Realgam Tower.
Plusle was inspired by Wes and Rui's actions, and in gratitude, as well as a desire to help the other Pokémon Cipher kidnapped, Plusle and Duking decided that the little Pokémon should go with Wes and Rui.
Duking also makes an appearance in Pokémon XD. He has become an avid wild Pokémon fanatic after discovering Poké Spots, where wild Pokémon can appear. After explaining to Michael how catching wild Pokémon works in a news report at the Rock Poké Spot, he helps Michael find the other 2 Poké Spots. He also provides Michael with the Spot Monitor application for his P★DA.
Afterwards, he returns to his home in Pyrite Town, and keeps to his back room, making Poké Snacks. He also asks Michael to catch a Trapinch, a Surskit, and a Wooper for him (the three of which are the rarest Pokémon available at each Poké Spot) as well. If caught, they can be traded to him for a Meditite, a Shuckle, and a Larvitar, respectively.
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