Question: how do you evolve eevee into umbreon in fire red?
Answer: 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. So just trade your Eevee to Ruby, Sapphire, or Emerald.