Introduction:
I wanted to try something different after I got bored with my last team. ( http://www.smogon.com/forums/showthread.php?t=103870 ) That meant no Nidoking and no Ferrothorn/Gliscor/Jellicent defensive core. I gave many things a try and settled on trying to build a rain team from the ground up, since until now I've avoided weather-based teams. My plan was to wound my opponent using bulky pokemon and entry hazards so that my rain-boosted sweepers can clean up lategame.
Changes in red
Team at a Glance:






Team Building:

I started, obviously enough, with Politoed. The bulky set to keep rain up and tank opponents.


I added bulky Dragonite to take advantage of the weather straight away and force switched with Dragon tail.



I added Ferrothorn to take advantage of the rain for fire defence, set up hazards and deal with opposing water types and take water and grass attacks.




Chansey for taking any and all special attacks, inflicting status and passing wishes to politoed, ferrothorn and dragonite to keep them alive as long as possible.





Gengar added as a spinblocker and to force switches with sub/disable.






Haxorus as my lategame sweeper. The plan was, one dragon dance and nothing would be able to live through entry damage and Haxorus' attacks. It didn't quite work in practice, so that's where the changes come in.






I decided that the team needed to hit harder, faster, so I made some changes. I introduced Scizor and Volcarona as my cleaner-uppers, and switched Dragonite from bulky to mixed rain wallbreaker.






I then changed Ferrothorn to Forretress with Rapid spin in order to accommodate Volcarona's weakness to SR. Chansey was cripplingly weak to Close Combat, which had been causing major problems, so I switched it to Tentacruel for toxic spikes and an extra rapid spin, but soon dropped rapid spin for ice beam since it was redundant if i play Forretress correctly.

Politoed (M) @ Leftovers
Trait: Drizzle
EVs: 252 HP / 240 Def / 16 Spe ( from 252 HP / 252 Def / 4 SDef )
Bold Nature (+Def, -Atk)
- Scald
- Toxic
- Perish Song
- Protect
Standard bulky Politoed. I either lead with this or Forretress, depending on the opponent's team. There isn't really much to say, everyone has seen drizzle politoed before.

Forretress (M) @ Leftovers
Trait: Sturdy
EVs: 252 HP / 252 SDef / 4 Def ( from 252 HP / 176 Def / 80 SDef )
Sassy Nature (+Def, -Spd)
- Spikes
- Stealth Rock
- Rapid Spin
- Gyro Ball
Gets the hazards up and blows the opponent's hazards away. With rain up I can leave it in against HP fire opponents and set up easily. Gyro ball for espeon/latios/tyranitar but not a lot else.

Vaporeon (M) @ Leftovers
Trait: Hydration
EVs: 248 HP / 252 Def / 8 SDef
Bold Nature (+Def, -Atk)
- Rest
- Scald
- Ice Beam
- Toxic
Switched Tentacruel for this. Rest is amazing for walling and it can absorb status all day long.

Dragonite (M) @ Leftovers
Trait: Multiscale
EVs: 252 Atk / 252 SAtk / 4 Spd
Rash Nature (+SAtk, -SDef)
- Hurricane
- ExtremeSpeed
- Aqua Tail
- Roost
I abandoned a bulkier set for this wallbreaker. Doesn't mind tyranitar/Hippowdon switching in because of aqua tail, then leaves politoed to reinstate rain. Hurricane is standard abuse, there's not a lot that can withstand it. Extremespeed is a lifesaver also. I try not to waste Dragonite unless I have to as strong priority is immensely useful endgame.

Volcarona (M) @ Leftovers
Trait: Flame Body
EVs: 4 HP / 252 SAtk / 252 Spd
Modest Nature (+SAtk, -Atk)
- Quiver Dance
- Fiery Dance
- Hurricane
- Bug Buzz
I was browsing the strategy dex and saw this set and thought "who in their right mind would use this!?" The next day I was using it and loving it. Not walled by heatran nearly as much in rain. A few quiver dances and heatran can't dent it more than leftovers can heal it, then Hurricane hits hard and can confuse. I love it. If it gets going not a lot can stop it at all.

Scizor (M) @ Leftovers
Trait: Technician
EVs: 252 HP / 40 Atk / 216 SDef
Adamant Nature (+Atk, -SAtk)
- Swords Dance
- Bullet Punch
- Bug Bite
- Roost
Currently testing Jirachi and Breloom as replacements
Threatens opponents like mad, forcing switches through hazards and hits hard with priority. Everyone has seen scizor before, I'd only be repeating the strategy dex if I elaborated.
I have to go now, which is why the descriptions are so brief, but if you need me to elaborate just say so in the comments and I'll justify decisions I've made etc.
Any suggestions to improve would be very appreciated. One thing I will say is that I'm having particular problems against Rotom-W, so anything that will help against it would be lovely.
Thanks!