Duskull, the Requiem Pokémon of Hoenn, can be found in the wild Pokémon Go. Yes, Duskull can be shiny Pokémon Go!
No member of the Duskull family sees any use in battles, although there is a pretty good shiny version. Note that you need a Sinnoh Stone to evolve Dusclops into Dusknoir.
What is the shiny rate for Duskull in Pokémon Go?
According to old research from the now-defunct website The Silph Road (via Wayback machine), the shiny rate for Pokémon on a normal day is approximately one in 500. Duskull is not a confirmed Pokémon that receives a “permaboost” (meaning that it is a rare spawn and therefore receives an increased shiny rate).
What can I do to attract more shiny Pokémon?
Unfortunately not much. It seems to be a coincidence. Catch rates for Shiny Pokémon are set by developer Niantic and are typically only increased during special events such as Community Days or Safari Zones, or during Legendary Raids. There are no consumable items that increase the rate of Shiny Pokémon.