Question: how to evolve eevee into jolteon in ultra sun?
Answer: Eevee turns into Jolteon when you give it a special stone called Thunder Stone. To get one, head to the back of the caravan found at the Fossil Restoration Center in Route 8. Alternatively, you can get one by playing minigames at Poké Pelago or buy one in Konikoni City for 3,000 credits.