There are several ways to evolve an Eevee in Pokemon SoulSilver...
1) Use a Waterstone on it to get a Vaporeon (Water)
2) Use a Thunderstone on it to get a Jolteon (Electric)
3) Use a Firestone on it to get a Flareon (Fire)
4) Level it up during the daytime with sufficient happiness to get an Espeon (Psychic)
5) Level it up during the nighttime with sufficient happiness to get an Umbreon (Dark)
In order to get Leafeon or Glaceon, you must trade them over onto SoulSilver from Pokemon Diamond Version, Pokemon Pearl Version, or Pokemon Platinum Version.
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You have to get it from a friend who has Pearl/Diamond/Platinum
Can only evolve from Eevee if it gains a level while on Route 217, so you must trade an Eevee over to Diamond, Pearl, or Platinum and evolve it there, since there is no Route 217 in HeartGold and SoulSilver.
Evolve from Eevee by happiness at day time.(4:00am to 8:pm)
You cant evolve it into glaceon unless you bring an ice stone over from a game that has more stones than silver, (silver doesn't have to many.) after transferring it, eevee will evolve. The best you can do without an ice stone is espeon(if it evolves in day) or umbreon (if it evolves in night).
Pikachu into Raichu, and Eevee into Jolteon. I don't recommend evolving Eevee into Jolteon. Espeon is way better.