So I've used this team and slight variations of it a few times on Pokemon Online and it's kinda stuck onto me since. It's my first shot at making a weather team and also my first OU team (I like UU better for some reason). I've really been wanting to use Rotom - W and I also like the VoltTurn strategy, which I know works pretty well in the rain. But mind you, VoltTurn isn't the main focus of this team. So without further ado, I present my team:
My obvious lead and weather starter. His main job is to stay alive throughout the match and keep the rain going, hence the defensive set. I've seen it being used with Specs and even Scarf though I found the latter a tad bit gimmicky. It uses the standard Toxic/Protect stall strategy. Perish Song forces the opponent to switch out, thus crippling setup sweepers and choiced sweepers alike as opposed to Encore which is useless while dealing with the latter. I've also encountered a SubToxic variant of Politoed on PO though I've need tried it myself.
Got this set on Smogon. Though it might seem odd on a rain team, this Rotom serves as a means to deal with opposing rain teams which have given me a lot of trouble before I decided to make my own. I specifically hate Tornadus who trolls big time with Prankster Taunt and STAB Hurricane. The EV spreads are also kinda weird but I don't know much about damage calculations so meh. I've also used the TrickScarf variant which is marvelous against teams that don't use rain. It's also a better job at VoltTurning than this one and keeps dragons at bay with HPice so I wouldn't mind swapping the two if that's a good idea...
So this guy is like the only physical attacker on board. He hasn't much to fear in the rain save for Volcarona and probably some Heatran. His main job is to take care of Latias and Celebi. He's a great physical attacker all round and takes care of whatever the others can't handle. Like I mentioned earlier, I wanted to try VoltTurn and this is the best thing that comes to mind. It also complements Rotom very well. I've been using this set since Platinum came out and is a personal favorite of sorts.
Tentacruel's main job is to lay down Toxic Spikes and also function as my Rapid Spinner. Scald burns that which cannot be poisoned. Protect grants 1/8th healing when used. Like Politoed, This guy's main job is to stay alive and lay down spikes or spin away entry hazards when required. It can also be helpful against opposing rain teams. The speed EVs are to help lay down spikes faster and outpace certain threats like magnazone and breloom.
Volcarona @ Life Orb
Ability: Flame Body
EVs: 252 Atk/ 4 SpDef/ 252 Spe
My other sweeper. Hurricane gets 100% accuracy and helps deal with the likes of Virizion and Breloom. Bug Buzz is my main STAB and takes down Celebi. Fire Blast screws Ferrothorn and opposing Scizor, even with rain in play. She's also really powerful under the sun and helps me beat other sun teams. She also happens to be the reason I need to keep Tebtacruel alive and healthy at all times. Flame body also helps shut down a lot of physical sweepers although Volcarona isn't really meant to be taking hits.
Slowbro makes an awesome physical tank. He's also my favorite Pokemon from UU although he does great in OU as well. While Flamethrower is normally used in place of Psyshock, I have chosen it for two reasons, the first being that flamethrower's power is severely weakened by rain and the second reason is that besides Scizor, the entire team consists of special attackers and thus being walled by the fat pink jerk. Ice Beam is my best, albeit shaky, answer to dragon types.
Please rate, comment and criticize freely. And while you're at it, please recommend something I can do about dragon types and Gastrodon. Thanks