Rain Dance and Taunt are both excellent options as well. With Taunt you can completely shut down Magic Coat-less Deoxys-D, Gyro Ball-less Ferrothorn, Blissey / Chansey, SubToxic Gliscor, and a host of others. Tornadus-T is at its scariest when it doesn't have to deal with adverse field conditions, and Taunt helps Tornadus-T to keep its field clear early in the game, giving its team time to mount enough offensive pressure to prevent the opponent from having enough time to set up Stealth Rock. Stealth Rock will of course go up in a lot of games, but the early pressure of having to deal with an unimpeded Tornadus-T early game , not to mention all of Taunt's myriad uses, make it worth considering, especially if your team is hazards-weak.
Rain Dance is obviously good, but I think its underestimated even given how obvious of a "good" move that it is. It's an auxiliary accuracy-fixer, forces Tyranitar / Ninetales / etc. to switch out and eat hazards damage, yada yada yada. It's not so amazing that it should be considered an essential move, but it gives a valuable safety net, especially in the lategame when you might want to avoid having to switch to Politoed.
Also Hidden Power Ice is great for smacking Thundurus-T as well.
Rain Dance is obviously good, but I think its underestimated even given how obvious of a "good" move that it is. It's an auxiliary accuracy-fixer, forces Tyranitar / Ninetales / etc. to switch out and eat hazards damage, yada yada yada. It's not so amazing that it should be considered an essential move, but it gives a valuable safety net, especially in the lategame when you might want to avoid having to switch to Politoed.
Also Hidden Power Ice is great for smacking Thundurus-T as well.