HP:79 Attack:115 Defence:70 Special Attack:125 Special Defence:80 Speed:111
Tornadus' brother in arms, Thundurus and its fellow genie share both a stat line and an ability. This, however, is where the similarities end. With Electric typing and a very different movepool, Thundurus is far more of a direct offensive threat, and has had such an impact on the metagame that it is the first fifth gen Pokemon to earn itself suspect status in playtesting. Watch this space, Thundurus may not be found in the OU section for much longer.
Playing with Thundurus:
Thunderus' most powerful set, the one which may earn him a banning, is by far the Nasty Plot variant. Capable of OHKOing most of the tier after a single boost is one thing, but when you can shut down Blissey long enough to go +6 and 2HKO it is another. Thunderus can also run an effective mixed set, capitalising on the raw power it's base stats give it than a boosting move.
Playing against Thundurus:
Blissey with Ice Beam is one of the few things that can outright counter Thundurus, while it is also susceptible to faster Ice and Rock attacks in general like Tornadus. Quagsire also ignores it's boosts, has access to Stone Edge, and only fears the rare Grass Knot. If used in conjunction with rain, removing it's weather will essentially rob it of it's primary STAB option.
HP:89 Attack:125 Defence:90 Special Attack:115 Special Defence:80 Speed:101
The final genie plays substantially differently to its brethren, but is no less lethal in the right conditions. A powerful physical sweeper in it's own right, with an excellent stat line and movepool, Landorus really comes into its own in the sand.
Playing with Landorus:
Getting a sandstorm going is the first step to making the most out of Landorus, in order to activate it's ability. The equivalent of a Life Orb boost to it's two most popular moves is certainly nothing to sniff at, and capable of wreaking havoc in conjunction with Swords Dance or Rock Polish. It's excellent SpAtt stat also complements its sets well, allowing it to best many physical walls with even an unboosted Hidden Power. Choice sets also see a lot of use for their ability to do quick immediate damage, but outside of sand it is almost always outclassed by Terrakion in this role.
Playing against Landorus:
A unifying theme between the djinn is that Ice Shard wrecks them, and Landorus is the most susceptible of the lot. While he is not slow by any stretch of the imagination, base 101 isn't greatest speed tier for a sweeper with a quad weakness, and as such he can be easily revenge killed by a lot of threats. Which is just as well, because trying to wall Landorus in the sand is pretty damn difficult.
HP:125 Attack:130 Defence:95 Special Attack:130 Special Defence:95 Speed:90
The runt of the OU litter, although you wouldn't think so looking at those stats. Kyurem is the first Pokemon to join OU because it is too broken for UU, rather than earning its spot here. Despite having a very impressive combination of offences and bulk, with one of the best stat lines this side of Ubers, common weakness and limited options really hold Kyurem back. It is, however, a beast in the Hail both offensively and defensively.
Playing with Kyurem:
You really need to play to Kyurem's strengths to make the most of it. That strength is it's prowess in the hail. A STAB Blizzard off of a base 130 SpAtt with 100% accuracy can maul a hell of a lot of OU, and coupled with Draco Meteor gives Kyurem a truly formidable STAB combination. The set can be rounded out with Focus Blast for Steel types and Dragon Pulse for more consistent STAB. Life Orb or Choice Specs are the way to go for offensive sets like these, allowing Kyurem to capitalise on its raw power. On the other side of the coin, Hail stall is very effective, with it's excellent bulk, the ability to make 101HP substitutes, and Protect and Pressure for easy PP stalling. With Toxic Spikes support, Kyurem can wear down huge quantities of the game.
Playing against Kyurem:
Kyurem originally fell into UU because it had a hard time fitting into OU, and little has changed in the time it was gone. Most notably, Fighting types are all over the place, capable of tearing Kyrem apart with their STAB attacks. The Stealth Rock weakness doesn't help either. Steel types in general have an easy time walling Kyurem, forcing it to revert to the unreliable Focus Blast to hit them.