Hold on a sec here
If you are trying to cut, ya, pizza is horrible.
If you are trying to bulk, there is nothing wrong with pizza. Just make sure there is lots of meat and cheese on the pizza.
#1 rule if you are (all things being equal) trying to bulk
Its better to eat bad than to not eat at all.
So if you are in a stretch where the healthy protein sources are looking disgusting (lean meats, protein shakes, etc.) by all means wolf down a pizza in two separate meals.
Just remember that if you do that, you are going to get fat as well. But if pure muscle gain is your goal, its the best way to go.