Espeon is a Psychic-type Pokémon. It is one of the Pokémon that evolves from Eevee. This Pokémon is extremely loyal to its trainer if it considers it worthy enough. It will read the air currents and predict its opponents next move by its sensitive hair or using the tip of its forked tail. The orb on its head glows when using its supernatural psychic powers. When its power is exhausted, the orb grows dim. The voice that I think that would fit  should sound adventurous and determined. Also kind of playful sounding and not too high of a voice.