Can Voltorb be Shiny in Pokémon GO? At this point, no. Despite being featured in the Tricky Pokémon event, you can't actually get a Shiny Voltorb.
Can Voltorb be Shiny in Pokémon Go?
You will be able to get Shiny Voltorb at the Philadelphia Safari Zone, thought that event has been postponed due to the global COVID-19 pandemic. While Voltorb will have an increased spawn for the Tricky event, you can't get a Shiny Voltorb.
According to Niantic, ticket holders who do not request a refund will be able to partake in the special Pokémon spawns at home on the original event date on May 8. The ticket will be good for the postponed event.
May 8 will be the first day anyone can get a Shiny Voltorb, so you'll have to wait for players in the Philadelphia area to get a few for trades if you can't make it to the event.
Shiny Voltorb is blue instead of red. It looks like a Great Ball rather than a Poké Ball.