There are 3 different types of cards: Pokemon cards which are separated into Basic, Stage 1, and Stage 2 categories, Energy Cards, and Trainer Cards which represent items and other miscellaneous effects
When a card says damage cant be prevented, it means what it says: Combat damage and noncombat damage will occur
The counters are on the tracker in the art, not on the creature itself
Equipment that was attached to it will remain unattached
Like most Magic: The Gathering cards, the value of Gishath, Sun's Avatar depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (The Lost Caverns of Ixalan)