Eevee evolution, vaporeon or espeon?

Vaporeon without a trace of doubt. Its the best water pokemon we have in this game, and doubt it will change anytime, cause PROBABLY Kyogre will not have a fast water move (only if water spout, muddy water, origin pulse, aqua ring, surf or waterfall turn into fast water moves, not charge moves).

Even if Kyogre get a water charge move, its still a bit too far of its release and Vaporeon will still be good. Espeon is good, but soon enough we will have Mewtwo for that psychic role.

Vaporeon is still the strongest water Mon. For psychic mons, new two is the way to go.

Same answer. Vaporeon is a staple in any solid player's arsenal. Good bulk, good attacks, just does damage and wins fights. Make it Vaporeon.

Vaporeon or Flareon.

If by high IV, you mean 96% with 15 ATK or at least 98% overall, use the name trick.

If you made it this long without using the name trick, you might as well make it count.

Before just saying Vape like everyone else, I'll ask if you have a good Alakazam or two. Espeon is still one of the better attackers in the game, and after you've done the name trick for it, you'll need to walk an eevee for 10k before you can ever get another one, whereas vapes are T3 raid bosses and can be evolved randomly.