Leviathan
Water Elemental
Leviathon is a water serpent and attacks heavily against all enemies. He has the Recovery skill which when junctioned can make your party very strong indeed.
It is important to draw Leviathon when you can as if you miss the water serpent you will not be able to pick it up again until you reach Ultimecia's Castle. Leviathon can be drawn from Master Norg when you fight him in the basement of Balamb Garden. It must be drawn from Norg himself after his pod has been broken open