I've tested these raim stall team me,bers and they work REALLY well!
Politoed @Leftovers
Nature:Sassy
Ability:Drizzle
EVs:252 HP/ 200 Def/ 58 Def
IVs: 0 Spd
-Perish song
-Encore
-Scald
-Protect
I completely agree with benlisted about the P-song + Encore combo on Politoed. I've been trying it lately, and it has really wrecked a lot of things. I haven't tested the 0 IVs and sassy nature against a Ttar yet, so I'm not sure if it can underspeed him and get it's weather up. Protect is helpful for stalling for more TSpikes damage, scouting the foe's next move, and helping P-song count down.
Parasect @Leftovers
Nature:Impish
Ability:Dry skin
EVs: 252 HP/ 100 Def/ 158 Sp.Def
-Leech seed
-X-scissor
-Substitute
-Spore
Parasect (like everyone else has said) is AMAZING in the rain! Once you get enemy weather inducers out of the picture, he can stall out entire teams! Spore is really awsome for stopping troublesome pokemon cold. X-scissor is really useful against Latias, Latios, Celebi, and Reuniclus.
Ferrothorn @Leftovers
Nature:Careful/Impish
Ability:Iron Barbs
EVs:252 Hp/
-Leech Seed
-Power Whip
-Spikes/Stealth rock
-T-wave/Protect
Sorry for not finishing the Ev spread. I don't have access to PO right now. T-wave ruins a lot of sweepers that don't have Substitute, and can give him a free turn of entry hazard set up. Power whip helps against other rain teams, and I once swept 4 pokemon with it. Leech seed + Leftovers recovers a good amount of health, and if you swap T-wave with protect you can scout the foe's move and recover even more.
Toxicroak @Leftovers
Nature:Jolly/Adamant
Ability:Dry Skin
EVs: 252 Atk/ 252 Spd/ 6 HP
-Drain punch/Cross chop
-Sucker punch/Ice punch
-Swords dance
-Taunt/Substitute
Toxicroak in the rain is an awesome sweeper. He can OHKO Tyranitar with Drain punch or Cross chop. Sucker pumch is helpful against Psychics who think they can OHKO you, and is good for revenge killing. Drain punch is great for helping toxicroak heal even further and is great if you can't get behind a sub, or if you are running taunt. Ice punch is helpful against Grass-types that could pose a problem for your water-types, and is helpful against Landorous and Gliscor. But Ice punch is illegal with Drain punch, so you would have to run cross chop instead. I ahven't tested Taunt yet, but it seems like it would work well against things like Ferro or Forry.
Tentacruel @Black sludge/Leftovers
Nature:Bold
Ability:Rain dish
EVs:252 HP/ 18 Spd/ 234 Def
-Surf
-Toxic spikes
-Rapid spin
-Protect
Ahhh... Tentacruel. He's one of the most awesome TSpikers and Rapid spinners under the rain. He's really helpful with the ability to remove TSpikes just by switching in, and can then rapid spin other entry hazards away. I'm not sure which item heals more HP, black sludge or lefties. Black sludge does have the bonus of hurting trick users. Protect is useful for, like I said before, scouting the foes next move, getting more rain dish and Black sludge/Lefties recovery, and stalling for more TSpikes damage.
Vaporeon
Nature:Calm
Ability:Hydration
EVs:252 HP/ 252 Sp.Def/ 6 Def
-Wish/Rest
-Protect/Scald
-Acid armor
-Roar
THose are all I can think of off the top of my head, but I'll update this if I think oif any more.
I've been looking for a good spinblocker, and eviolite dusclops and disable gengar are the closest I've gotton to a good one. Dusclops is useful for completely shutting down Drain punch and sucker punch toxicroak, and gengar can shut down a lot of other things. I'm going to test Choice Band Spiritomb, and I'm wondering what else it helps against besides Starmie? I imagine it could do good damage to latias or latios, who I have had a hard time with if they carry thunderbolt. If someone could post a good CB spiritomb set that would be great.