S.H.
**Kids this age, do what is called "Parallel play" They do not yet 'know' how to play interactively. It is developmental. They don't know yet, social 'rules' nor do they even have "impulse control" fully developed yet.
Toddlers do not know, automatically, 'how' to manage their emotions. Emotions are not even fully developed at this age.
So you have to arm him with 'skills' on HOW to manage his emotions...as well as encouraging communication and expressing himself, verbally... so he can TELL you, what is irking him, or even good/happy feelings. TEACH him the 'names' for feelings/emotions/frustrations.
ie: happy, sad, grumpy, frustrated, tired, hungry etc.
Actually give him the words to 'practice', because otherwise a child does NOT know what to say. ie: "I'm grumpy... I need quiet now...", "I don't want to share.... right now...", "I am frustrated because...." , "I'm tired...." etc. THEN, with him, redirect him to something else... and TEACH him alternate ways of doing things or handling things.
Of course, he has to learn, that biting/scratching is NOT good. Tell him hands are not for hitting/scratching... but for hugging.
Unless a toddler KNOWS alternate ways of handling situations... just mere punishing/time outs/scolding, will not make much sense to them. You need to teach them... "how".... to navigate... themselves.... in frustrating or happy moments too. Giving the child SKILLS and teaching them.
What if: someone told you to row a boat around some obstacles and then go to the finish line by a certain time? Well, unless you practiced it and had a 'strategy' about it and someone taught you the basic skill of rowing and steering a boat... you would not know "instantly" HOW to do it, right? Nor would you do it efficiently or like an 'expert' who has been doing it for YEARS. And what IF you had to row the boat down some rapids???? You would not know how.
Well, same for a Toddler... who does not yet, know how to MANAGE their emotions nor frustrations... nor social 'rules.' So you need to teach him, that. AND practice WITH him about it. Not only, when something happens. Role play with him.... to practice....
It is a stage... but unless you teach him skills about it and how to manage it.... and his frustrations... scolding/punishing/time outs, will not work, conclusively.
You need to give a child wings to soar.... BY giving him SKILLS and teaching him HOW to navigate himself, with his emotions and social situations. Not just 'expecting' that a Toddler will know how, by themselves.
My son, from only 2-3 years old, could tell me "Mommy, I'm grumpy...", "Mommy, I don't want to play with sister now..." etc. And I respected that and praised him for it... because even if 'grumpy' he could EXPRESS that in words, articulating himself/his emotions... and seek out alternatives. For example.
A toddler is like a rock collecting moss... practice with him. And as time goes by, he will learn and attain better skills for handling his emotions/social situations.
all the best,
Susan