Max spd gyara? Er... I don't think so. I wouldn't give it more than 222 spd, to outspeed ttar. With perfect IVs and adamant, that's 96 EVs.
Personally, I like torterra as a curser, although SR looks pretty viable.
Oh, wait.... this is for a double battle? Metadour, your suggestions are for single battles, mostly, and until I noticed that it was a double battle, myself, I had no idea (what? I initially came in here, saw you just listed pokemon, and decided to try to expand upon what was already said).
Ok, now that that's out of the way, welcome to cheap doubles tactics 101. Class has started.
First off, double explosion is a deadly stat in doubles. Or... it was in adv. Not so sure about that in d/p, but I'm sure it still holds potency, although I'm not so sure the concept is really "double" explosion anymore. Since pokemon are no longer sent in immediately after being killed, you are no longer able to kill 3-4 pokemon on turn one. However, a single explosion with your partner protecting will deal some major damage to your foes. A common staple of explosion teams is a reversaler (lucario will be perfect for this job), which carries endure and a salac berry, and proceeds to wreak havoc after an explosion. You'll have to experiment a bit for yourself, but because lucario is steel type, it should be able to take a weaker explosion, which is where you will have the ability to swords dance. The following turn is when you use endure (at this point they will likely be attacking you, anyway, as you have both low hp and an sd up, so it works out rather well). If you think you can kill both pokemon on your opponent's side with only reversal and an attack from one of your other pokes, do it, then do another endure/explosion the next turn, and continue as such. Choice Band on one or two, and Life Orb on the rest will be excellent items for your pokemon, seeing as the CB provides pure power, whereas the LO will allow you to vary your actions a bit before going off, which is critical on a pokemon like gengar, who will want to hopefully kill something with a tbolt or shadow ball first, and some of the more fragile boomers will have to protect, rather than just take the hit like gengar and metagross can.
Double intimidate is also highly potent. It makes most physical attackers nigh worthless, and easily picked apart, particularly if you lead with a team like Gyarados/Salamence, which can then double earthquake (provided your foe doesn't have a flier). Depending on the poke, you may want either CB or LO. Something like tauros without a lot a of diversity will enjoy being able to CB Return, however something like mence would prefer a Life Orb, since it wants to be able to switch moves.
Now, I should mention the importance of the move protect in a double battle. If you suspect your foe will be taking two attacks toward one of your pokemon, a simple protect will waste your opponent's turn, while you still get to attack with your partner pokemon. Also, if you expect an explosion from your opponent, a double protect will remedy the situation quite nicely. Although messing up with your protects can cost you the match.
Weather teams are extremely potent in uber battles, but since you don't have access to Groudon/Kyorge, I wouldn't bother.
A newer tactic which has come to light because of DP is abuse of the move Trick Room. Essentially, all of your pokemon should be super slow, preferably with speed reducing natures. On turn one, you have one pokemon use the move Trick Room, then just **** with everything else you have, which are all very slow, very powerful (probably very sturdy) pokemon. Rhyperior is a choice pokemon for this kind of team. You can combine this fairly easily with the explosion tactic outlined above, just be sure to leave out the reversaler (unless you want to use one with very low speed, of course, which would also work fairly well). In fact, now that I think about it, a slow reversaler on a trick room team would be extremely deadly, as you'd be able to use a liechi berry as your held item. I'd imagine something like Hariyama would fit the bill nicely, just be sure to min speed it (when EV training focus on Atk and SDef, as you want to make sure it drops to 1 HP when you use endure). Once again, pretty much everything else should have LO or CB (or Choice Specs, since there are slow SAtkers). Consider having two trick room pokes on the same team, since you'll need to send in the TRer again midway through the battle to revitalize the effect, and let's face it... switching sucks in doubles. Everything is SO offensive that it's difficult to do without taking a large amount of damage.
Well, that's pretty much it. I covered some of the biggest, most deadly strategies I know of in 2v2. As I'm sure you've noticed, many can overlap, and I'd like to make it clear that this is not all there is. However, you'd have to talk to someone who regularly plays 2v2 to find out about some of the more intricate strats that go on in a 2v2 battle, and how effective each one is.
Oh, and as one last thing... I mentioned having most of your pokes hold Life Orb as an item. I'm aware this item is hard to come by, and I'm not even sure where you get it (I'm not too far in DP, myself). Once you get one LO, you can practice the cloning glitch, then use it after you've gotten good with it to obtain multiples.
