After Destroying rome in the 2rd Punic war.could Hannibal successfully grab the roman fleet and March on Carthage and declared himself king or emperior
1) The term of Emperor didn't existed before Rome created it.
2) Hannibal didn't wanted to destroy Rome, just reduce the size of the Roman republic.
So let's assume that Hannibal conquers Rome and forces the Senate to give up Sicily, Sardinia and Corsica and to recognize the independence of Capua and the other Italian allies.
3) Hannibal had some influential ennemies even in his home city.
4) Carthage was, by then, a republic and will stay it unless Hannibal uses force to seize power and become king.
5) If he does this, a civil war will soonly erupt in the Carthaginian Empire opposing the supporters of Hannibal (mainly his army) and his ennemies (mainly the senate of Carthage and its troops).
6) During the civil war, the Romans will have enough time to punish their former allies and rebuild their empire.
7) At the end, we will have either a Kingdom or a Republic of Carthage shattered by Civil War and a Roman republic having recovered from the Carthaginian campaigns.
8) Rome will continue to expand in the Mediterranean and still become the most important power, even if this happens a bit slower than OTL.
9) Carthage will be destroyed and punished even harsher than OTL, because they not only beat the Romans in a battle, but in a whole war.
No Hannibal, don't do this. Just don't do this.