The smallest unit of hoplites was the file, usually of eight men. Eight across and eight deep formed a sub unit with various names. There were regional variations. Groups of these small blocks were organized by territories or tribal titles or standing regiments such as the Spartan Mora of 600-640 Spartans.
Small detachment battles such as the Athenian disaster in Aetolia, the Spartan disasters at Sphacteria island or Lechaeum fit skirmish games, and the ironic part is these small actions were more decisive at times than massed battles which often settled nothing
In the Macedonian army the smallest tactical units was the syntagma, a 16 wide by 16 deep square formation that was the building block of the taxeis (regiments or battalions) of six or more blocks each. At Alexander's battles he usually had 6 taxeis of various strengths of phalangites. The hypaspists had a similar organization but based on 1024 strong chiliarchies.
At the Granicus river one syntagma of phalangites was detached to cross the river with the cavalry. In sieges parts of the phalanx stayed back in phalanx to cover the besiegers who were building works, these would have operated in detachments, spread across the front.
In the Bactrian campaign small detachments of phalangites marched with the cavalry columns, but the massed phalanx wasn't used again until the battle in India.
Macedonians were trained to use pikes spears and javelins, so their armament is usually assumed to fit the given task. Detachments would be very fluid in arms, formations, and how they approach their task from skirmishing to forming up, so they would leave the pikes behind in the baggage train.