Today's CotD is Porygon Z's less insane evolution, Porygon 2. The original upgrade to Porygon offers quite a nice effect; its Poke-Power, Download, let's you use basically another Supporter by discarding it. Being able to play more than 1 Supporter a turn is a significant advantage, considering you usually only can play 1 a turn. With a Porygon2 or more on your bench, you can significantly speed up your set-up. Stat-wise, Porygon 2 is ok; 70 HP is a bit low for a Stage 1 these days imo, +20 to Weakness means Gallade and Lucario OHKO it most of the time. No Resistance (anyone else notice lots of cards these days have no Resistance?), and 2 for a Retreat Cost is a bit steep. Its sole attack, Speed Attack, is overpriced at 2 for 30 damage, but then again, you'll never hopefully have to attack with Porygon2.
Modified - 8/10 (Arguably more playable than its evolution, and a great support Pokemon)
Limited - 6/10 (Unless you get a lot of Supporters or a Porygon Z, might not want to use this here. Weak attack and low HP means he won't see much action)
Unlimited - 1/10 (No point in using him here)