Can I use Team Rocket's Porygon-Z's "Reconstitute" Ability to discard two cards from my hand if I have no cards in my deck?
No, because the discard is a cost to use its Ability. If you aren't able to draw a card, then you can't just pay the cost of the Ability.
Source: Destined Rivals FAQ; TPCi Rules Team (2025-05-29)