D'oh! I was talking about Gliscor; my bad.
Anyway, don't use Dark Pulse on Tornadus; it doesn't have noteworthy coverage. A neutral STAB Hurricane does more than a super effective Dark Pulse (a suupereffective Dark Pulse has a base power of 160 while a neutral STAB Hurrican has 180 base power). Replace that with U-turn to get out of the battle once you think Tornadus has done enough for the battle.