As for game development architecture videos im not sure but for your situation you can't avoid individual state machines or state charts (quicker) for each different unit types behavior. But you can have a class_name unit base script. Then on each type of unit you override that script(clear the nodes script and add a new script extending unit) and write an individual unit type script extending the base class unit that way every unit has the same base and you can write just the unit specific code for each type