RAW each of the Skeletons can take one of the following actions on its turn:
Shortsword*
Shortbow*
Attack (with a Weapon or Unarmed Strike)*
Dash
Disengage
Dodge
Help
Hide
Influence
Magic
Ready
Search
Study
Utilize
When you get down to it that is a pretty complex list of options end-to-end with slightly shy of 270 million different combinations for 4 skeletons.
* Note RAW the "Shortbow" and "Shortsword" actions are actions unique to skeletons and found in their statblock, while the "Attack" action is an action afforded any creature.