00 Flour is a European designation, Triple C. In France and Italy, in particular, they have a whole range of flours identified numerically based on the protein content.
In the U.S. we have only three general classifications. Cake flour, which is a low protein (i.e., low gluten) flour made from soft wheat. Bread flour, which is a high protein flour made from hard wheat. And All-Purpose, which is a combination of the two.
There are other special purpose flours, but they're not generally available.
For pizza either All Purpose or Bread Flour will work, as you want some gluten development.