I think porygon was in the beginning of the latios and latios movie when Brock was talking.
"Ash and Porygon-Z! The perfect weed smoking companions!"
I think that's enough appearence to Porygon, but Porygon-Z should make it since the people who got the seizures overcame their fear or something.They would ban porygon-2 from the tv show, but they wont ban porygon-z. Simply because it doesent really remind you of porygon except for its eyes and name.