Should my nephew get Umbreon or Espeon?

Heres an idea: Get an Eevee, save, then go get one of the two and see if he likes that one. Then, reload, and go get the other one. Let him pick which one he likes more. Umbreon is a Dark-Type Pokemon, and Espeon is a Psychic-Type Pokemon. Hope that helps! :D

Umbreon

Espeon is MUCH better in the (Special) attack department, and Umbreon is MUCH better in the defenses.

Since defense doesn't mean much against in-game trainers (except for maybe at the Battle Frontier,) go with Espeon.

Espeon because it is so much cooler and better and stronger. Also, its attack is much stronger. I have heart gold but I'm still trying out how to evolve it before lvl 15. Lvl 15 is when all the Evee-evolutions learn their basic element attacks, for example: Flareon (ember), Vaporeon (water gun). Espeon learns Confusion and there's a lot more lvls until it learns another psychic move so if you miss lvl 15, your screwed & it'll be super hard to train it. Hope i helped!!!

if he's into to defensive pokemon then id go with umbreon which i like and he doesnt have a good moveset but if u or him has tms such as shadow ball, moonlight,dark pulse,or psychic than i would probably go with him

Espeon has a good movesets and an insane sp. attack but his physical defence and attack is really low and with the right movestet i think theyre both unstoppable but i choose umbreon and my moveset on him will be:shadow ball, dark pulse, psychic, and moonlight so if i were him id definately go with with umbreon. and untill u get the move psychic(you get it in saffron city after beating the jhoto elite four go into mr. psycics house and get the tm, of course, psychic) i'd go with a move like head butt(move tutor in ilex forest) or quick attack

-hope i helped you nephew in denial

espeon if he is offensive they can learn lots of different types to.

umbreon if he is defensive let him experiment with both by saving and playing then load and try the other one.

i prefer espeon because its part of my eeveelution team on platinum.

I would say Espeon :)

unless you can get a good ghost pokemon because in my opinion those are the best ones

Umbreon because it is a Dark type and has fewer weakness'

Umbreon is waaaaaay cooler!