If you could give Ash an Eevee, What would it become?

[PkmnTrainerV]

My preferred choice would be Sylveon, like I said before, or Espeon. They’re the ones Ash would have to put work in. Flareon and Jolteon are too boring considering the Pokémon we've seen Ash with, and he’s not the person to use a stone evolution unless the Pokémon itself requests it. Leafeon and Glaceon are meh to me personally. Umbreon would be fine but Gary already has one and that one gets enough media attention as it is.

Not to mention I’d love to see Ash using Pokémon whose main line of offence is psychic and fairy offensive moves, since we've seen very less of that. The last prominent psychic move user I remember is Noctowl back in Johto. I hope we see more of Gengar using it too.
Psychic and Fairy moves have good potential for !Ash-improvisations and it’s a pity we've seen so little of that.

 

[techitisJ]

I think Espeon or Umbreon would suit him well, with the friendship-based evolution. Also, he hasn't trained much of either of these two types (actually I don't think he's even trained a psychic type). I know Gary and Ash being rivals is long gone too, and it's hard to say if they're even foils of eachother anymore, but Espeon would be a cool call back to that and to the in-game character he was loosely based off of. So if Ash were ever to get an Eevee (let's face it though, I think the Eevees just belong to the Pokegirls now), this would be the one.

But, while I was thinking of this response I thought of a really cute scenario I would like to see happen. So Ash obtains an Eevee, in whatever way at some point, and Pikachu becomes somewhat of a big brother/mentor to Eevee (something I think he has done in recent series, but the last I recall was Misty's Togepi). Pikachu cares for him, battles with him a lot, shows off to him, and Eevee just gobbles it all up, particularly enamored by Pikachu's display of electric attacks. So, when Eevee is ready to evolve, Ash uses the thunderstone that he was given to evolve Pikachu (I'm pretty sure he doesn't have this one with him anymore, or anyone, just not completely sure. Let's just say he had a thunderstone in case Pikachu wanted to evolve) if he wanted to evolve, to evolve Eevee. And the newly evolved Jolteon is just absolutely stoked to be like Pikachu. It's cute, wholesome, and kind of symbolic. Usually, a mentor wants to see their student grow to be as strong as them, and using Pikachu's thunderstone on Eevee to help him continue to grow stronger like his mentor, would just be such a cool charm.

Plus, I feel like there's this unspoken rule that Ash can't train another electric-type Pokemon. He trains multiple Pokemon of the same type before, and has trained legendaries and mythical, and even aliens. I think he can train another electric-type Pokemon.