It would seem that there is in fact a way to force an evolution of your Eevee. The Eevee Brothers
from the original anime 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 thought this was bullshit, but people in the local PokeGO community are reporting a 100 percent success rate, including a dude who named all six of his Eevees Sparky, and all six evolved into Jolteons (thanks, dude).
So I’m willing to try it and pass it along.
i did this last night with Pyro and it worked. heard from a local player it worked 12/12 times for him and people he knew. i think it’s legit