Wrath - Kefka, because he hate......haTE......HATE!!!

Lust - Irvine, because he is freakin' womaniser.

Envy - The unsents.

Greed - Yuffie. As stated above.

Pride - Kuja. All that needs saying is done by YTDN.

Sloth - Dunno.

Gluttony - ......err......nuff said.