Unlike Pokémon Colosseum where your starter Pokémon was both Espeon and Umbreon, in Pokémon XD you instead just get a single Eevee.

In Gateon Port, you will find a store that will offer you the items that allow for you to evolve your Eevee. Unlike the main series games, you do not need to evolve Eevee through a time-based friendship evolution for Espeon and Umbreon, but there are in fact special items that will evolve it into them. Choose wisely as you cannot undo the evolution

Pic No. Name Item
#134 Vaporeon Water Stone
#135 Jolteon Thunder Stone
#136 Flareon Fire Stone
#196 Espeon Sun Shard
#197 Umbreon Moon Shard