Umbreon would defo be suited best to a Neutral nature over anything that would decrease its defenses.
That said, Hasty is a really bad nature for a Vaporeon... So i guess ya might need to try for a third Shiny Eevee.
That said, Hasty is a really bad nature for a Vaporeon... So i guess ya might need to try for a third Shiny Eevee.