Everyone posted up Politoed, so I wanted to show something different.
Electrode@Damp Rock
Ability: Aftermath
Bulky Spread: 248 HP / 252 Spd /8 Def or 8 Sp. Def
OR
Special Attacker: 252 Spd / 252 Sp. Atk / 4 HP
Modest/Timid Nature
Moveset:
- Taunt
- Thunder
- Rain Dance
- Volt Switch
Electrode is an amazing anti-lead! First use Taunt to cripple any hazard setters. Then use Rain Dance to get up Rain weather up. Thunder is great STAB and has amazing accuracy under Rain. Volt Switch is good for switching out. I'd recommend the Bulky Spread because it enables Electrode to set up Rain more often.
Zapdos@Damp Rock
Ability: Pressure
EVs: 248 HP / 240 Sp. Def / 20 Spd
Modest / Gentle Nature
Moveset:
- Rain Dance
- Thunder
- Roost
- U-turn / Volt Switch
This Rain Dancer is somewhat different. First you set up Rain Dance. Thunder is there for obvious reasons. Roost gives nice recovery. Here's the dilemma: You can either run U-turn, so that you won't be blocked by Ground-types (but it does less damage). You could also go with Volt Switch for more damage (but you'll be blocked by Ground-types). It's your choice. Note that you should go with Gentle Nature if you're going for U-turn and Modest for Volt Switch.
Thundurus@Damp Rock
Ability: Prankster
EVs: 200 HP / 252 Sp. Atk / 56 Spd
Modest/Timid Nature
Moveset:
- Taunt
- Rain Dance
- Volt Switch / Hidden Power [Ice]
- Thunder Wave / Thunder
This set is quite similar to the Electrode set. It's another great anti-lead with Taunt (priority because of Prankster). Rain Dance also gets priority! Volt Switch has amazing STAB and can switch out to another Poke. Hidden Power [Ice] provides coverage. Thunder Wave is a good support move and Thunder has amazing damage and accuracy under rain. It's your choice.
Note: I'm not sure if some of these Pokes are available in OR/AS, so you'll have to transfer from previous generations.
Hope I helped!