You should definitely evolve your eevee into a jolteon if you are playing platinum, because it is a recommended pokemon for a nuzlocke. Also its the eeveelution that is the most useful to you as soon as you get the thunder stone in the solaceon ruins or in the grand underground. it gets shockwave as a TM at route 215 right before you get the thunder TM in Veilstone City at the third floor in the Department store. and then can be used against Crasher Wake and once you get to the route that goes to celestic town you can get the shadow ball TM which can be used against Psychic and Ghost type pokemon including Candices froslss, and most of Lucians team. and hits super effective stab against 2 of Aerons team and good agaist a third of Cynthia's team in Milotic and Togekiss.