The town of Obsidia, nestled in a quiet area of Unova, has always been a simple Pokémon town, with it's own little system of going about things, the farming Pokémon would provide food for the town, the Pokémon skilled in craftsmanship, kept the farmer's home in good repair, while they also did small jobs for the rest of the town. Those skilled in arts kept then town looking good, while also keeping nature in tone with the city.
But lately, some strange things have been happening, at first it wasn't noticeable, some crops would go missing, or perhaps a resident would go missing, but the townspeople always had some excuse as to why things were happening. They always had a logical reason, that is until their mayor, a Gigalith, was found completely torn to shreds in the middle of town. The Mayor's remains were scattered into a note, a clue per se, it read "Foolish townspeople, the Mayor didn't accept my demands, maybe together you'll figure out what to do."
Appalled, the town made a pledge to their Mayor's remains, to find the murderer, make him pay, and take the town back to it's former glory. Of course, not everyone in the town wants the town back to the way it was.