Quote Originally Posted by Nalien View Post
Wasn't Sin basically Leviathan? I seem to remember it basically being a summon Yu Yevon used to protect himself while he turned himself into a purple balloon.
Not quite.
Sin is not exactly Water-based, but instead, Gravity-based, given that in order to get made, it had to attract a LARGE quantity of pyreflies, as well as having a Final Summoning as the base of it (which also explains why it had attacks such as Giga Graviton and the like).