Bronzong, that funky-looking bell-shaped Pokemon, I think has quite some potential. Stat-wise, he is solid for a Stage 1, with 90 HP, +20 Weakness to Psychic (not good, but at least Gardy can't OHKO you unless they play a Strength Charm), -20 Resistance to Fire (great VS Magmotar and friends), but a rather heafty Retreat Cost of 3 Energy. Its first attack, Pain Amplifier, is one of the sole reasons you'll want to run Bronzong; for no Energy at all, he will place 1 damage counter on each of your opponent's Pokemon that already has a damage counter. This is great in damage spread-oriented decks, as Bronzong can continually up the pressure for free. Of course, you'll have to get damage counters on your opponent's Pokemon first, which isn't too hard considering the wide variety of choices (Zapdos, Prinplup, Empoleon, etc.). And when you're ready, you can Rare Candy that Omastar you've been saving all along for mass KOs. Coating in general is an ok attack, dealing 60 damage for 1 Psychic and 2 Colorless Energy and a reduction in damage by 20, but you'll generally want to stick with Pain Amplifier and setting up your other Pokemon instead.
Modified - 8/10 (A great card that has potential)
Limited - 7/10 (Pain Amplifier is a bit tricky to use, but you can also use Coating to stall as well)
Unlimited - 1/10 (Why would you use him here?)