In the event Leonnatos, pursuing his own agenda, comes to his aid. Diodorus (18.14.5) is specific in Leonnatos' recruiting (again likely reflecting his source) stating that Leonnatos
Leonnatos has not recruited in Asia Minor and nor has he done so in Thrace - the latter being in some turmoil and a work in progress for Lysimachos (14.2-4). Diodorus is also specific in that Leonnatos recruited "many additional Macedonian soldiers". That the bulk of these were infantry and phalanx infantry is likely as the battle description implies. Diodorus presents this largely as a battle of cavalry in which the Thessalians defeated Leonnatos and his cavalry. Diodorus then states (15.4):crossed over, therefore, into Europe and went on to Macedonia, where he enlisted many additional Macedonian soldiers. When he had gathered together in all more than twenty thousand infantry and fifteen hundred cavalry, he led them through Thessaly against the enemy.
There would appear to be a substantial component of Macedonian phalanx infantry in this army. How large is anyone's guess, but if it was difficult for Antipatros to hire mercenary heavy infantry or recruit allied infantry, it was no easier for Leonnatos. Especially as his recruiting was done in Macedonia (this might well have been a similar recruiting drive to that of Philip V for Kynoskephalai - it was certainly that important). Antipatros then retires to Macedonia with both forces. That's a certain 13,000 plus whatever Lennatos brought to the conflict. A conservative guess would be 4 - 6,000. In the following year Krateros brings his "over 10,000" veterans to add to these figures. Discounting the army left with Sippas we have something in the order of 27-29,000 Macedonians and possibly more.the Macedonian phalanx, for fear of the cavalry, at once withdrew from the plain to the difficult terrain above and gained safety for themselves by the strength of the position.
In 320 Antipatros and Krateros march into Asia to what, for them, can only have been a showdown for empire with the royal army of Perdikkas. This army had to be of a decent size and will have had a substantial number of Macedonian phalanx infantry as its core. Now Diodorus (18.29.6) says the army was divided into two parts and gives the impression these are equal parts. Plutarch (Eum. 6.3) is clearer in stating that Krateros took the larger part of this division. Both writers are clear that Antipatros was sent to Kilikia and Diodorus (ibid) makes it quite plain that the rejoined forces will than have marched on Perdikkas with the help of Ptolemy. Thus Krateros took the larger part of the infantry - 20,000 the "greater number of which" were Macedonians (I set aside Hammond's rather forced translation for the sake of his argument) . Here we might posit somewhere in the order of 12,000 - certainly Eumenes was in no way interested in taking on this phalanx despite his cavalry numbers. We might also suggest that Antipatros kept some 2 - 4,000 with himself giving a total of 14-16,000 and leaving some 13,000 - 15,000 in Macedonia
If these numbers are in the ballpark, Antipatros is clearly able to gift 8,500 of these to Antigonos and return with some 5,500 - 7,500. On Krannon's estimates, there are some 13 - 15,000 either active or able to be called up for service and hence Polyperchon's reluctance to take the field against the 26,500 strong Aetolian/Thessalian army (18.38.3). Added to this are the 3,000 men Antigonos returns to Macedonia. Without additions for age groups or whatever comprised Sippas' army, there are possibly 21,500 - 25,500 available for call up in spring 318. Again, these are conservative estimates but estimates they remain. In any case, it is not "impossible" for Polyperchon to have 20,000 Macedonian infantry at his disposal in spring 318.