How to Force Your Eevee to Evolve Into Your Choice of Eeveelution!
It would seem that there is in fact a way to force an evolution of your Eevee.
From the original anime the Eevee brothers were named Rainer, Pyro, Sparky and they owned a Vaporeon, Flareon and Jolteon respectively. If you nickname your Eevee either Rainer, Pyro or Sparky, your Eevee will evolve into that desired Eeveelution!
Sparky = Jolteon
Rainer = Vaporeon
Pyro = Flareon
I have tried it on a few Eevees and so have friends, and we’ve seen a 100% success rate. Feel free to give it a try and post back here with results!
Edit: It would seem a lot of people are reporting that their first Eevee evolved into the correct evolution, but the second Eevee may not have. I think it’s possible you may only be able to obtain one specific Evolution at a time, and not obtain the same one twice in a row. Please continue to post results so we can try to get some real data!