4 HP / 252 Atk / 252 Spd
Acrobatics, Tailwind, Taunt, Protect
4 HP / 252 SAtk / 252 Spd
Thunderbolt, Hidden Power (Ice 70), Grass Knot, Thunder
Tornadus is your basic Tailwind Tornadus. I actually don't use Tailwind that much though because most of my team, including this Tornadus, is usually fast enough without Tailwind. Most people use Adamant, and most people EXPECT Adamant, but in my experience Adamant REQUIRED Tailwind, whereas this Jolly one still 1HKOs every Hitmontop/Amoongus/Grass Type/Bug Type/Fighting Type/Terrakioin(with Gem)/etc that it comes across, and outspeeds them without Tailwind. The Tailwind is really just there for other Tailwind teams, or to outspeed a pesky scarfed mon or whatever. Having only one type of attack has never really bothered me. The other 3 mons do a fine enough job of handling any Steels or Rocks.
I used to use that same Thundurus T set up there for a Thundurus I. But even with a pretty good SAtk and Specs I still had consistent problems with bulky mons. Electric/Ice/Grass is a great attacking type combo to choose from, but even then I'd still never 1HKO, and rarely 2HKO anything bulky. But those extra 20 SAtk points really do help. Obviously, it depends on how they're trained, but I've noticed a markedly increased 1HKO and 2HKO rate (which has lead to a hillariously increased DC rate). I'm sure you're thinking, "Why is Thunder up there?" Firstly, because there are quite a few rain teams on wifi. And secondly, because I've occasionally found myself in the situation where it came down to my Thundurus versus their last mon, and Thunderbolt just didn't cut it. Honestly, I've out of a couple hundred battles on wifi, I've used it maybe two times, but without it those two times I would have undoubtedly lost. Generally, Thunderbolt, Hidden Power, and Grass Knot cover whatever I need 99% of the time. Its just that 1% of the time where I can either hope for a 70% chance to 1HKO, or give up and hit Run.
If you'd like a couple vids of these two doing their thing, here are two recent ones.
I've used that Tornadus I since B/W came out. It has been through probably a thousand battles on different carts and tournaments and VGC. Its done spectacularly every time. Its done so well that I seriously have trouble building new teams WITHOUT that Tornadus. I've used Thundurus I for just as many battles on Random Doubles, until last week when I started testing Thundurus T. I've recorded 88 wins since putting that that Thundurus T on my team, probably 50ish DCs, and 23 losses. Although obviously Thundurus T wasn't on my team every single battle, I usually do end up choosing it, sometimes just to see how much it would do against Pokemon X. It has done e x a c t l y what I had hoped it would do, and now my team has no problem whatsoever with bulky teams.
Now, I know from talking with you that your playstyle is different than mine, but these two have been absolutely GOLDEN for me on wifi.