Introduction
It's funny. I've been around for a while but have never posted a RMT. Well that changes today. I've been playing around with this team for a little over 2 months now and I've been having quite a bit of success with it. I've decided to retire the team and let you lovely people criticise and possibly improve it. I hope you enjoy. :)
Team Building Process

After learning of Politoed's new ability Drizzle I was compelled to make a team based around taking advantage of the ever lasting rain. Politoed can hit surprisingly hard with its STAB Water attacks thanks to the rain, and can also take quite a few special hits thanks to its 90 HP and 100 Special Defence.


First thing I wanted on my team was an offensive Pokemon to abuse the rain. Keldeo fitted the bill; 129 Special Attack, 91/90/90 defences, the magical 108 Speed and Water STAB. It was born to be on a rain team.



A sturdy steel type that can set up entry hazards, cripple opponents' speedy sweepers and has its fire weakness reduced to x2 thanks to rain? A perfect fit for a rain team.




I wanted to see how effective the Prankster ability would be in 5th gen and Thundurus has just the right moves in Taunt and Thunder Wave to make good use of it. 100% accurate STAB Thunder was just a bonus.





Starmie is my favourite Pokemon of all time. I always try to incorporate it into my teams because I love its combination of speed and coverage between 3 moves.






I wanted to see just how effective Technician Breloom could be in this new generation, but I was too often confronted by Chandelure switch-ins that would put an end to any sort of set up before it even began. I was also having great difficulty handling Contrary Serperior at the time.






I thought Scizor was a good fit for the team as it could scare away Serperior thanks to its powerful U-Turn and easily take care of Latios and Latias who would otherwise give my team some trouble. However, I didn't like Scizor's performance against opposing rain teams, more often than not it would simply become death fodder.






Genesect seemed to be exactly what I needed. It could scare away or take out Serperior, could KO Lati@s and performed well against opposing rain teams thanks to its speed.
In Depth View
Thundurus (Farfetch'd) @ Leftovers
Prankster
-Timid-
252 SpA / 4 SpD / 252 Spe
Thunder
Hidden Power [Ice]
Taunt
Thunder Wave

Thundurus (Farfetch'd) @ Leftovers
Prankster
-Timid-
252 SpA / 4 SpD / 252 Spe
Thunder
Hidden Power [Ice]
Taunt
Thunder Wave
Thundurus more often than not assumes the lead role of the team. Prankster Taunt shuts down opposing lead that like to set up entry hazards immediately, barring Magic Coat Deoxys-S, with Thunder and Hidden Power Ice for the pseudo Boltbeam. Thunder Wave is used to paralyse a threat before being taken down, such as Choice Scarf Latios, so that the rest of the team can handle it easier. I have previously used a Nasty Plot set as well as a Specs set but the ability to priority Taunt, especially Whimsicott and Sableye, and paralyse opposing threats far outweighs the benefiits of the other sets, at least in my eyes.

Politoed (Farfetch'd) @ Leftovers
Drizzle
-Calm-
252 HP / 252 SpD / 4 Spe
Scald
Hypnosis
Toxic
Encore
I like to bring in Politoed as soon as I can to set up the weather and put something to sleep, preferably the opponent's Ferrothorn. Thanks to 5th gen's sleep mechanics putting something to sleep is pretty much KOing them. Toxic is to wear down opposing Water types, especially Burungeru, making them easier to OHKO. Encore is for if the opponent thinks they can use Politoed for set up bait and to stop lead Deoxys-S dead in its tracks. Scald over Surf as the 30% burn is always a nice surprise.

Starmie (Farfetch'd) @ Life Orb
Natural Cure
-Timid-
4 HP / 252 SpA / 252 Spe
Hydro Pump
Ice Beam
Thunder
Rapid Spin
Starmie has always been a massive threat in OU, and 5th gen is no different. It spins away the opponent's entry hazards, if they manage to set them up, and wrecks face whilst it's at it. Ice Beam and Thunder are there to hit whatever resists Hydro Pump for super effective damage. Starmie's Hydro Pump in the rain is ridiculously powerful, OHKOing the likes of Garchomp (without entry hazards), Bulk Up Conkeldurr (>90% of the time, guaranteed with Stealth Rock) and Bulky SD Scizor (with Stealth Rock).

Ferrothorn (Farfetch'd) @ Leftovers
Iron Barbs
-Impish-
252 HP / 48 Def / 208 SpD
Stealth Rock
Power Whip
Leech Seed
Thunder Wave
The bane of just about every sweeper not carrying a Fighting or Fire type move. It's no surprise that this guy is #1 most used. After many EV combinations I decided to stick with those in the analysis. I used to use an all out physically defensive set but it was simply overkill. With these EVs Ferrothorn easily survives HP Fire from the likes of Latios and Espeon with more than 50% remaining and can hit them back with a crippling Thunder Wave or a powerful Power Whip. I prefer using Stealth Rock to Spikes on this set as everyone now has an answer to Ferrothorn so it rarely has the time to set up multiple layers. Leech Seed for recovery and to gain the upper hand in a stall war.

Keldeo (Farfetch'd) @ Leftovers
Justified
-Timid-
20 HP / 252 SpA / 236 Spe
Surf
Secret Sword
Hidden Power [Psychic]
Calm Mind
I was blown away by how good my little pony is on a rain team. After a single Calm Mind there is very little that can stand in its way that hasn't invested very heavily in Special Defence. I chose Surf over Hydro Pump as between itself and Starmie I was missing too often. I previously used a Life Orb set with Hydro Pump with great success (OHKOing specially defensive Jirachi after a CM) but the fragility and unreliability of the set put me off. Secret Sword is an unbelievable move for a special attacker for its ability to destroy Blissey and Eviolite Chansey and severely dent Ferrothorn. Hidden Power Psychic is there solely to take out Toxicroak, who otherwise destroys my team. As I use HP Psychic I have to sacrifice a point in speed so I run 236 Spe EVs to outspeed base 105s such as Mienshao.

Genesect (Farfetch'd) @ Choice Scarf
Download
-Mild-
196 Atk / 96 SpA / 216 Spe
U-Turn
Thunder
Ice Beam
Explosion
I use a Mild nature with 216 Spe EVs so that I reach 288 Spe, enough to outspeed Jolly Gyarados, and I use 96 SpA EVs to ensure Ice Beam KOs max HP Dragonite that doesn't have Multi Scale active without the Download boost. The rest is then dumped into Attack to make U-Turn and Explosion as powerful as possible.
U-Turn is such an amazing move on a Choice Scarf Pokemon, even better on Genesect thanks to STAB and possible a possible Download boost. Thunder for opposing Water types and any Gyarados that thinks it can DD up and sweep under the rain. Ice Beam as previously mentioned is for Dragonite, as well as Garchomp. Although Explosion isn't as good as it was in gen 4 I like to use it on Genesect to net a surprise KO on the likes of Blissey/ Chansey and Toxicroak, who otherwise don't fear Genesect.
Conclusion
Well there you have it Smogon, my first RMT. As for threats all I can say for sure is that Ferrothorn gives me problems from time to time and Breloom can be a real pain if the opponent leads with it when I decide to lead with Ferrothorn/ Politoed. Other than that I generally have an answer to any threat that comes my way. I hope you enjoy tearing my team apart and I thank you in advance for your constructive criticism.