How to get Adaptability on Porygon-Z in Platinum?

Question

I just started my Platnium run and I want to use a Porygon-Z with adaptability. Is there a way to predict what my Porygon’s ability will be once fully evolved? Like if its current ability is download, will it stay as download or change into adaptability?

Comments

Not a full answer, but https://bulbapedia.bulbagarden.net/wiki/List_of_Pok%C3%A9mon_by_Ability
As far as I know, Hitmontop is the only Pokemon species that shares an ability as its pre-evolution, but an individual Hitmontop can't have steadfast if it evolved from a Tyrogue with steadfast.

Answer 1

Anecdotally, your Porygon would stay as Download its entire evolution line.
Using this website:
https://www.serebii.net/pokedex-dp/137.shtml
Porygon has Trace and Download as its abilities. As you can see with this website:
https://www.serebii.net/pokedex-dp/474.shtml
Porygon Z has Adabtability and Download. Trace would become Adaptability in this instance. You need a new Porygon.

Comments

Formally: a Porygon with Download has been assigned ability slot 2, and since the species Porygon-Z has Download in slot 2, that Porygon will always evolve into Porygon-Z with Download. A Pokemon's ability slot cannot change when it evolves.
And to get a new Porygon, you can just breed the existing one and you'll eventually hatch one with Trace (slot 1).