Vaporeon - Aqua Tail vs Hydro Pump

Most will tell you to not power up Vaporeon (if you can resist) until you get close to level 30. You will find stronger eevees in the wild.

As for moveset, it comes down to personal preference. Aqua Tail is great if you try to dodge every move because it is very quick. It is also good on attack and defense.

I'm partial to the long, highly damaging charge moves, and thus prefer hydro pump over aqua tail, mostly because I'm lazy and prefer to do one big charge move and knock out that Arcanine, rather than 2 smaller charge moves. However, aqua tail is pretty damaging and relatively quick for a charge move, so if that's all you have, and she has decent IVs, it might be worthwhile to power up.

If you wait, consider: A) the probability of evolving a Vaporeon (doesn't seem to be 33%, even though "should" be), and then B) the probability of getting the "ideal" move set.

I only dodge charge moves and not even all of em, so hydro pump fits my play style better.

Im not big iv fan, cus moves are more important for me, so my hydro pump vaporeons have 80%, 75%, 64% and 57% iv's and im totally happy with em.

I think against bigger opponents with moves like body slam or dragon claw aqua tail is better. Against hyper beam and solar beam id say hydro pump is prolly better depending on playing style. Against smaller mons I think Hydro is hands down better.
Once you hit level 30 there will be 880 CP Eevees in the wild.

Aqua tail is a good all round move - good for attacking and defending. Hydro pump is slightly better for attack and water pulse is supposedly better for defense, although I can't evolve one for the life of me - last three Evees all turned into Jolteons...