How you get Espeon in Pokemon Crystal?

Answer 1

You have to raise your Eevee's Happiness level to the highest possible point, and then allow it to level up during the daytime. To raise a Pokemon's happiness, you should visit your Rival's sister in Pallet Town (she'll groom it for free, which makes it happy). You should also visit the Underground in Goldenrod City, where there are Pokemon barbers who will charge a small fee to do the same thing once per day. Additionally, carry it with you and use it in battle. With some time, it will be happy and evolve. NOTE: If you raise your Eevee's happiness to max and allow it to evolve at night, you will instead get an Umbreon.

Train Eevee to level 50 without rare candies and give it lots of calcium, iron, ect.

Espeon= friendship day

Umbreon=friendship night