Complex sentence: In Pyrite, Shadow Pokémon are openly offered to winners of the town's Colosseum tournament-the local police force is powerless to stop the practice, so Duking (an influential man in Pyrite) asks Wes to enter the tournament and investigate.
Split into simpler sentences: In Pyrite, Shadow Pokémon are openly offered to winners of the town's Colosseum tournament. The local police force is powerless to stop the practice, so Duking, an influential man in Pyrite, asks Wes to enter the tournament and investigate.