This is fun!
Macedonians were the first to show what happens when you break a rigid phalanx line and then launch a fast attack through the gap when at Chaeronea Philip withdrawn a wing and pushed forward the other, fragmenting the Greek line. Of course, the Macedonian line was gone too, but it did not matter because they outmaneuvered the Greeks and pressed on an attack that annihilated them.
If I would be a later period Macedonian king facing the legions of the Middle Republic I would not insist on cavalry units. They are expensive, take a lot of time to train and are of limited use in the narrow valleys of Greece where the campaign will be fought. I would have no reason to fear roman cavalry because they would not bring lots in oversees campaign and their Greek allies don't have much. At the same time I know that Hannibal gave some painful lessons to the romans about cavalry so they would be hard to surprise and would know how to defend themselves. Several cavalry units for foraging, scouting, flank protection and pursuit would be enough.
The Macedonian army consisted mainly of the sarissa-armed phalanx supported by the excellent light infantry provided by the mountain tribes and Greek mercenaries/allies equipped with spears and narrow Celtic shields (an evolution of Iphicrates-style units). This is not inferior to the armament of the legions that were still of the veliti/hastati/triari type with spears, shields and javelins. Both sides were mainly levy, mercenaries and allies so there was not much standardization of weapons, every soldier brought what he had at home.
The main areas of improvement would be the recruiting and training of soldiers and officers, organizational reform of units and sub-units and of corresponding ranks, creating legion-like large, permanent units with several types of soldiers so they are capable of independent action and carrying less important campaigns to give combat experience to the army and a proving ground to the officers.
I would try to fight the battle in a easy defensible position, with the flanks covered like in a valley.
I would deploy the army in depth with light infantry in front as skirmishers, or covering the flanks, with a main line of sarissa phalanx and a second line/reserve of more mobile units including cavalry to plug the hole in the phalanx if the romans break it or to pursuit them if they flee. The fact that often Greek and Hellenistic formations lacked reserves is rather an error of leadership then an inherent fault of the phalanx.
But the most important things I would do would be to establish friendly relations with Rome because in the case of a war I'm definitely in trouble, they are relentless and, just in case, to create a strong fortification in a city as far as possible of Rome, but with a good port, in a strategic location that is easy defensible something like ... I don't know... Byzantium?