In Pokémon FireRed and LeafGreen, however, the time function is completely absent, allowing it to be more like the Generation I games. This also makes it impossible for Eevee to evolve into either Espeon or Umbreon in these games.
In RSE there is time system so just raise it's happiness during the night to get Umbreon and during the day to get Espeon
you can also trade one from Pokemon Colosseum/XD:Gale of Darkness
So just trade your Eevee to Ruby, Sapphire, or Emerald. You can also evolve it through stones obtained in Pokemon XD.