Man, Hydration Vaporeon gets no love.
As not-metagame-big-or-important Vaporeon is, it still maintains a humongous niche in Rain as either going two ways: A ridiculously Bulky Special tank that gets an auto-Refresh every turn in Rain as well as free 99% recovery or a surprisingly strong Tank that can abuse the hell out of Life Orb + Rest. The biggest detriment to all of this is the very small existing number of Rain stall teams that require it. Based off of August statistics, the metagame is split in half in terms of Stalliness, so Rain stall makes up around 10% of the metagame, and most of the denizens on the Rain Stall are Poli/Tenta/Ferro/Bliss/Glis/Filler. Vaporeon has to compete heavily for that one spot on the team. While it is bulky, it can't take Spec Meteors all day, so Blissey/Jirachi still stands. Tentacruel has too many benefits over Vaporeon, as Tentacruel can take Toxics, set up hazards, spin, and recover 12.5% every turn in rain, whereas Vaporeon just takes status and not wall much.
Why am I arguing with myself? Friggin' 1 A.M.
Oh, and Flareon should get Kudos, too, for finally getting Guts. Although it's still crap and Guts is still a crap way to boost your Attack, it still fires off pretty strong Superpowers and gives Fire Fang more bite (no pun intended).