carthiginian army in reality

[Decimus Attius Arbiter]

There was no typical Carthaginian army or formation. They used what they could recruit and what would work for the enemy they were facing.

[pezhetairoi]

Though from Theodore Ayrault Dodge's Hannibal, most field battles that Hannibal fought were based on the phalanx in the centre, with perhaps Cannae being the most high-profile exception. There is some indication that in the later Second Punic, formations split into more than one line in some of the bigger battles, and particularly at Zama, for greater depth, to counter the Roman triple line.

I think militarily speaking, the phalanx would probably have been kept in the centre where they could deliver their heavy frontal blow while the flanks would always be mobile melee infantry like the Samnites, Lucanians, Gauls and Iberians. It makes no sense otherwise to distribute your phalanx all over the place where their shock value would be diluted. Though it is questionable how long this arrangement might have lasted, considering the rate at which Hannibal was being attritioned/attrited/howeveryouspellit. I'm sure at a certain point his phalanx would have been whittled down till it was not very militarily effective.