Ate is intransitive in that sentence. There is no direct object."You ate pizza in the cafeteria" is an example of ate as a transitive verb (pizza is the direct object).
Originally, all of them love pizza.
"I ate pizza, and it was tasty."
Shane Warne
pizza!
ate pizza
they ate pizza
You will weigh 1 pizza more than you do now.
If you mean each ate 12 pieces, the pieces may have been of different sizes.
You can say "Comimos pizza para el almuerzo."
deyy ate pizza
I seriously doubt it.