Froslass was another hyped about card back before LA was released, and this one may actually prove the hype to be true. 90 HP is average for a Stage 1, +20 Weakness to Metal is ok since the only real contender you'd be facing is Metagross, and he's likely a tech line at best, no Resistance, and 1 Energy for a Retreat Cost. Destiny Bond for 1 Psychic Energy (have to discard an attached Psychic energy to use) is a decent way to stall, though your opponent can just simply opt for sniping at the bench, so it is a bit situational. Icy Breath is the reason you want to play Froslass; 40 damage for 1 Water and 1 Colorless energy is good, it puts your opponent's active to sleep (hey, a 50/50 chance of not being able to attack next turn is better than nothing) and it hits all the Pokemon on the opponent's bench for 10 damage. This makes it a very good card to use in damage spreading decks, along with an Omastar tech or TM TS-2. Good partners for Froslass include Ampharos, Bronzong, Yanmega, and Empoleon, all whom also spread damage as well.
Modified - 8.5/10 (A great card, expect to see some at the upcoming Battle Roads)
Limited - 10/10 (Easy to play if you can evolve into hit, and the status+spead aspect make it quite powerful)
Unlimited - 1/10 (No real reason to run this here, there are better options)