How developed should a 2 year old be?

My girlfriend's nephew is 2. He is not potty trained, he does not speak as well as other two year old children I have baby sat. When he pouts or acts up, the mother will hold him like a baby to her chest and not let go, trying to get him to be calm. Saying "Shhhh" and etc. The child is also hand fed mostly, although I do see him feed himself at times. In the mornings he is given animal crackers and quarter of a bagel. He does not eat meat and will not eat at the table unless his mother is there for him to sit on her lap. Therefore he wants her to feed him. Plus if he does eat, its something like pizza or a piece of toast. Nothing that will give him the proper nutrition. Also, he has eczema due to his mother not bathing him (he gets a bath once a week and his clothes are rarely washed). Plus he cannot dress himself, I've seen other two year olds put on their shoes by themselves by just being told by their parents. How far behind is he in terms of brain development?