I used 2 hooks for this cute hat decreasing the need for decreases. They are hook size US I and US P-15/11.50mm.
All six sizes can be worked from 1 skein in main color and 1 partial skein in contrasting color of Caron One Pound yarn. They are fitted as sized but not so tight that they squish your poor little heads so one person could potentially fit all 3 sizes snugly, fitted, and slouchy loose. Smallest size will fit loosely on a newborn head sized 14”.
There are a few photos of the hat as it progresses on the second to last page but not enough that I would call it a full photo tutorial.