Being the first instance of a virtual Pokémon, Porygon are rather clunky and unwieldy. They do not do much and can be slow at responding to commands. Porygon2 are more streamlined, and for the most part are self-sustaining. Porygon-Z can be a danger to themselves when glitching out, so trainers should be prepared to recall them into their Poké Balls if they do so. All members of the line should be returned periodically to their Poké Balls so that they can recharge.

-Professor Oak.