Politoed

When the VGC 2012 ruleset was announced, it didn't take long for Politoed to take hold of the metagame. With an entourage of Swift Swim Pokemon capable of utilizing Drizzle—that range from the humble Anorith to the mighty Kingdra,—Politoed is never in shortage of teammates to occupy vacant team slots. Politoed isn't just good for Drizzle, however, as it can deal major damage to anything without a resistance or high Special Defense with its STAB, rain-boosted Water moves, or support its team using moves such as Helping Hand and Icy Wind.

Politoed doesn't really have many issues either, besides the obvious weaknesses to Grass- and Electric-type attacks, such as those from Thundurus and Breloom. The only things that really trouble it are other weather changers, such as Abomasnow, Tyranitar, and Ninetales. Luckily, Politoed can surround itself with Pokemon that have great defensive synergy, allowing it to switch in and out to reinstate weather if need be, as well as having a good matchup type-wise against two-thirds of the other weather changers. Because of its versatility, power, and workable bulk, Politoed won't be budging from its top 10 position anytime soon.