That must have been quite a spectacle, herding all those elephants on to ships in Tunisia and taking them to Europe, then through the Alps. African elephants don’t take too kindly to being herded. Were those that Hannibal used imported from south Asia? Just asking.
The Romans were greatly surprised and terrified by the elephants in the first part of the war,but eventually they figured out how to fight them (letting them through the ranks, isolating, then killing them). I can't recall how the Romans got their own supply; it may have been a combination of capture and their own trading (Macedonians as middle-men?). For a while after Hannibal's defeat the Romans continued to use war elephants, but eventually gave them up.
Livy and Polybius are great ancient sources for Punic War histories.