>>38747554espeon was one of my favourites in gen 2!
I knew eevee had to evolve with happiness but I didn't have any good idea of what raised or lowered happiness so it actually took me a long time to evolve it. I carried this eevee past the elite four and into kanto, wondering what I needed to do to make it love me. (Not let it faint so much, first of all...)
But by the time the poor thing was level 45, and I was training in the area around mt silver... it finally evolved into a beautiful espeon! I was so glad that it learned psychic not long after, and I used it as my crowning pokemon to defeat Red sometime later.