Vaporeon: evolve Eevee normally with 25 Eevee Candy
Jolteon: evolve Eevee normally with 25 Eevee Candy
Flareon: evolve Eevee normally with 25 Eevee Candy
Espeon: set Eevee as your buddy, walk 10 km, then evolve it during the day
Umbreon: set Eevee as your buddy, walk 10 km, then evolve it at night
Leafeon: use a Mossy Lure Module, then evolve Eevee near the PokéStop
Glaceon: use a Glacial Lure Module, then evolve Eevee near the PokéStop
Sylveon: earn 70 Buddy Hearts with Eevee, then evolve it
Kanto trio name trick: rename Eevee to Sparky for Jolteon, Pyro for Flareon, Rainer for Vaporeon
Johto duo name trick: rename Eevee to Sakura for Espeon, Tamao for Umbreon
Sinnoh/other name trick: rename Eevee to Linnea for Leafeon, Rea for Glaceon, Kira for Sylveon
Name tricks work only once per evolution type
After using a name trick once, use the normal evolution method for more copies