Scorpions will appear in groups together, with Cobras, or with Bulls. They're found in the first half of the game.
They can poison you, so I usually don't bother fighting them. Other than that there isn't much strategy.
Scorpions are the same thing in every version. A scorpion is a real animal. It's an arachnid with a long tail it can use to deliver a poisonous sting. Scorpions of some kind appear in FF6 and Mystic Quest.