Duskull, the requiem Pokémon from Hoenn, can be found in the wild in Pokémon Go. Yes, Duskull can be shiny in Pokémon Go!
No member of the Duskull family sees any use in battles, though it does have 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?
As per old research by the now-defunct website The Silph Road (via Wayback Machine), the shiny rate for Pokémon on a regular day is approximately one in 500. Duskull is not a confirmed Pokémon that gets a “permaboost” (meaning that it’s a rare spawn and thus gets a boosted shiny rate).
What can I do to attract more shiny Pokémon?
Not much, unfortunately. It appears to be random chance. Shiny Pokémon catch rates are set by developer Niantic, and they are typically only boosted during special events like Community Days or Safari Zones, or in Legendary Raids. There are no consumable items that boost shiny Pokémon rates.