The Best Defense...

#1 a good offense. After doing a good bit of testing, I think I've come out with my first competitive OU team. It's fairly successful, and is based on the idea of having several strong pokemon that can counter many threats, and can serve a variety of purposes, all while retaining offensive power. ...Well, all except one of them, whom you'll see later. So without further ado, allow me to inctroduce my team:







Now for some more detail about each individual pokemon.

Metagross @ Leftovers Adamant Clear Body 252 Att, 252 HP, 4 SpD
Stealth Rock Zen Headbutt Meteor Mash Earthquake
Metagross is first and foremost a physical attacker that can switch in on powerful physical attacks and KO back. He also runs stealth rock for some utility, especially helpful if the opposing team has something like Dragonite or Volcarona, as it makes these threats easier to check, as well as racking up residual damage, since this team excels at forcing switches. Zen Headbutt works well for coverage against poison- and fighting-types that try to switch in and set up. Meteor Mash is a powerful STAB with a chance to raise Attack, and Earthquake gives useful coverage against other steel types, notably Magnezone, who could potentially switch in and trap Metagross.

Scolipede @ Focus Sash Jolly Swarm 252 Sp, 252 Att, 4 HP
Spikes Toxic Spikes Megahorn Rock Slide
Scolipede is my fast spiker, and a physical attacker too, when she needs to be. Focus Sash lets her get up a layer or two of spikes almost guaranteed; a couple of times she's managed to get up all the layers of both types of spikes before being KO'd. Her offensive presence also lets me deal with many issues faced by spikers: she can easily OHKO Espeon and Xatu, and is undaunted by Starmie, assuming her sash is still intact, or that she gets the first hit. She is also can take out three of the common weather leads--Tyranitar, Abomasnow, and Ninetails--with ease. If she survives later on, she can absorb Toxic Spikes, and switch into Toxic, giving her some later-game utility, too, if necessary.

Mienshao @ Life Orb Naive Regenerator 252 Sp, 252 Att, 4 SpA
Fake Out Hi Jump Kick Hidden Power Ice U-Turn
Mienshao is incredibly fast, incredibly powerful, and incredibly versatile. She can scout with U-Turn and Fake Out, not worrying about entry hazards because of Regenerator, can break Sturdy and Multiscale so that other pokemon can finish off an opponent, and sweep in her own right. I've also noticed that she has excellent offensive synergy with Yanmega; while both are frail, they compliment each other nicely. Mienshao is great at taking out Blissey and Chansey, which would otherwise trouble Yanmega, while Yanmega can outspeed and revenge kill faster threats that would otherwise take out Mienshao. Mienshao also deals nicely with Tyranitar and Gliscor, and with Fake Out, she can easily finish off weakened opponents.

Yanmega @ Leftovers Modest Speed Boost 252 SpA, 252 Sp, 4 Def
Bug Buzz Air Slash Hidden Power Fire Protect
Leftovers is a bit of an odd item to use on Yanmega, but I've found it works nicely for this team. Without a rapid spinner, Yanmega is sometimes forced to switch into Stealth Rock, which strips away half its health. But, with Protect, Yanmega can stall for more Leftovers recovery along with boosting its speed, and gives it a bit of extra staying power, along with letting it switch into Stealth Rock multiple times. Yanmega has great synergy with Mienshao; notably, with a U-Turn from Mienshao to Yanmega, Yanmega can easily OHKO Foretress through Sturdy, even in the rain. Yanmega also deals with Volcarona (Air Slash) after a Speed Boost or two. He boasts great coverage, accuracy, and power, and is also notable for being able to take out Venusaur in the sun, outspeeding it after a couple boosts. With his great coverage, especially alongside Mienshao, he can easily sweep at least a couple pokemon before going down.

Suicune @ Leftovers Bold Pressure 252 HP, 252 Def, 4 SpD
Scald Calm Mind Rest Sleep Talk
Suicune is my other tank. After a few Calm Mind boosts, she can tank even super-effective hits, and can do serious damage with Scald. The burn chance only helps. She also is useful against things that like to run Spore/Sleep Powder/Hypnosis, since she can use Sleep Talk until she wakes up, and not just be a sitting duck. I chose Pressure over Water Absorb so that she could PP stall; this way, even things that have Water Absorb as their own ability can be beaten, simply by using Calm Mind and Resting off damage until they are forced to Struggle themselves to death.

Hydreigon @ Life Orb Naive Levitate 252 SpA, 252 Sp, 4 Att
Draco Meteor Fire Blast Superpower Roost
A pretty standard Hydreigon set. Draco Meteor, with a Life Orb boost and STAB, pretty much 2HKO's everything in the metagame; if not, Fire Blast and Superpower hit their weaknesses. Fire Blast hits steel-types trying to wall Draco Meteor; it also means that Hydreigon stands up admirably to Jirachi and Celebi, providing they don't get time to set up. Superpower hits Blissey and Chansey hard if they try to tank Hydreigon's special attacks, and does super-effective damage to dark- and ice-types thinking to switch in and either set up or KO.

Some issues I've been having with this team involve Cloyster (if Yanmega has been taken out; I'm usually very careful to preserve him, though, if the opponent has a Cloyster in the first place), Substitute sets--especially Garchomp (Breloom isn't too much of an issue, though)--and Kyurem-B. Politoed tends to be hard to get through, too. Any suggestions and strategies for these guys, or any other glaring weaknesses you see, are welcome!