There is no real certainty of the size of force that Hannibal took with him, though estimates range from 20-40,000 infantry, 6-12,000 cavalry and 40 elephants. As Carthage was in North Africa, elephants were commonly used in war. They were a deadly weapon designed to charge, trample and generally create a sense of panic in the enemy, but from a Roman perspective, their use was a bizarre novelty.
In the event, although Hannibal did successfully negotiate the Alpine passes, his losses were considerable. Over half his army died in the severe, cold conditions, Hannibal himself was blinded in one eye, and it is recorded that only one of his elephants survived the trek. This lone elephant was used by Hannibal to ride in triumph into the city of Capua. What happened to the animal afterwards is unknown, although the elephant certainly didn’t participate in any of the subsequent fighting, which led to Hannibal’s eventual defeat. Via How many elephants did Hannibal take over the Alps?