You have to play with eevee in the day.
train your eevee in the afternoon
Espeon or Vaporeon.
evovle by makeing eevee happy & level up at morning
When Eevee loves you, level it up in the Morning.
Espeon cannot evolve.
Espeon is the psychic evolved form of Eevee. It is a psychic pokemon.
Typhlosion Gyarydos Ampharos Espeon Dragonite Tyranitar
Pikachu into Raichu, and Eevee into Jolteon. I don't recommend evolving Eevee into Jolteon. Espeon is way better.
umbreon and espeon
Pokemon blue is a 1st generation game. Espeon is a second generation pokemon. This means it didn't exist in blue.
In Pokemon soul silver you get eevee from goldenrod city, go to bills house talk to him (after you've met him in Ecruteak) and he will give you a eevee, level it up with max happiness during the day and it will evolve into espeon.
Cheating.