ESPEON OR ELECTRIVIRE?

Electivire because you have a perfect team so far. All it needs is a electric type because that would make your team ready for any type of combat. Psychic moves are super effective to very few Pokemon. Electric Pokemon are super effective to water Pokemon. It will be very rare for a Pokemon trainer to have a ground type Pokemon. One good move for Electivire is Giga Impact. Another is Hyper Beam or Earthquake.