Black 2 (though legal in black 1), Super single battle subway record: 73 wins.
Salamence, Choice Scarf (255 atk/speed, naive). Intimidate.
Flamethrower, Outrage, Fly, Earthquake
Articuno @ Charti Berry (255 def/speed, timid, 31 speed IV). Pressure.
Ice Beam, Sheer Cold, Mind Reader, Roost
Garchomp @ Focus Sash (255 atk/speed, jolly, 31 speed IV). Sand Veil.
Swords Dance, Outrage, Earthquake, Fire Fang
This team wouldn't work against a human opponent, but against the AI which almost never switches and often declines to set up, Fly is a very useful move, giving Salamence a decent flying STAB. Salamence is still probably the team's weak link - I see it get knocked out without first getting a kill more often than its teammates, and this particular one was initially designed to be a revenge killer, with Garchomp as lead. (Switching the two was what got this team to where it is now.) But I'm not having as much success with choice band - that speed boost means practically nothing's faster, and with intimidate and decent bulk it can usually take a hit unless it's up against ice.
Articuno is my second favorite pokemon after Pidgeot, but unless Pidgeot gets a fantastic move or item next gen it's never going to be viable. Articuno, on the other hand, tears through anything with good defenses and no Sturdy through the use of mind reader and sheer cold. Fast pokemon that can hit super-effectively give it trouble, as does status sometimes, but very few AI pokemon can OHKO it without a stone edge crit, or 2HKO without a type advantage. Add roost to the mix and it wins me a ton of matches, despite its lack of raw power and many weaknesses. (It also benefits from stealth rock being significantly less useful in 3v3.)
Garchomp is Garchomp. I think it's common enough on the teams the rest of you use that it needs no explanation. :)
The focus sash is for faster ice or dragon pokemon, or ice shard, and despite the bulk of this species its item still comes in handy. It also guarantees I can get off swords dance even if someone comes in with an ice punch/beam/fang. Sash is extraordinarily useful anyway, and it's on Garchomp instead of Articuno because Articuno very rarely would need it.
I can't say what its weakness is, per se. My last match I was defeated by a Gengar, who finished off a wounded Garchomp and outsped and 2HKO'd Articuno. There isn't an AI pokemon I try to avoid at all costs or anything like that. In the wi-fi subway, it has trouble with weather - Excadrill and Kingdra are both nasty with speed boosts, although Garchomp can revenge kill them if they aren't sashed - but in the super singles subway that strategy isn't used, so when I lose it's more about multiple counters in a row than any single one.