Porygon-Z is being cucked from OU where it rightly belongs because Gamefreak gimped Download, its most natural ability, so that it fails half the time.

Next gen, Download should be updated like so:
>On switching in, the user gets an appropriate stat boost, depending on which is highest among the foe's Defence, SpDef and Speed:
- If Defence; Attack raise
- If SpDef; SpAtk raise
- If Speed; Speed raise
- If there's a tie, the preference goes Speed>SpAtk>Attack