I dont think there is any evidence of Hannibal having troops that were armed with Sarissa (Macedonia style phalanx)

His African spearmen were most likely plain spearmen that, I guess, could use close order formations like the Greek hoplite phalanx.

Its stated that after his early victories these soldiers took Roman equipment but what precisely that means is not certain. It could be the armour and perhaps shields only or that they went over to fight in Roman style with sword and javelin.

That they were slowly winning at Zama before the cavalry came back could might as well be a matter of numbers, experience and/or fatigue as a good part of Scipios army had been involved in defeating the first two of Hannibal's lines.

At Trebbia it was the Gauls and Spaniards that was in his center and took the full impact of the Roman center desperately trying to cut a way through. And I wouldnt class the Gauls to be of same quality as his veteran African foot.

CBR