The abilities of werewolves in Innistrad that transforms them is a triggered ability and it can be responded to. In most cases, you want to ‘deal’ with werewolves controlled by an opponent in the preceding turn by casting one or two spells. However you can always wait until your one of these triggers goes on the stack and then play a spell or ability in response to this trigger.

The fact that this trigger uses the stack can also be useful for the controllers of these creatures. If you have a Rampaging Werewolf (A transformed Tormented Pariah) and your opponent has played two spells in the previous turn, you can untap, put this trigger on the stack at the beginning of the upkeep step, play Fling and sacrifice this werewolf while it is a 6/4.

Similarly, if you control a Nightfall Predator and your opponent has played two spells last turn, you can untap, put the werewolf trigger on the stack and use the Predator’s fight ability before it transforms into a Daybreak Ranger. If you do, the Nightbound Predator ability will resolve before it transforms and deal four damage to the targeted creature. Keep in mind that when it does transform it will not untap. (Currently the only transform effect that also untaps the creature is the transform ability of Civilized Scholar.) Also, the damage it received from the creature it fought with will remain on it. So if it fought a creature with power of two or more, it will go to the graveyard after it transforms.