Question: how to evolve eevee into jolteon in pokemon platinum?
Answer: Give one to an Eevee and at any level it will become a Vaporeon, Flareon, or a Jolteon, respectively. Espeon and Umbreon evolve when your Eevee is maxed out in happiness (two large beating hearts on your Friendship Checker app). Then, level it once either during the day (for Espeon) or at night (for Umbreon).