When Dante touched the homonuculus symbol on Gluttony's tongue, it seemed to have awakened the PURE sin within him and made him want to eat absolutely ANYTHING in his path, no questions asked. I'm guessing that all the sins have this ability, though most of them would be totally useless in these states. Gluttony and Wrath are probably the only ones who could do any serious damage. Let us take a look...
Gluttony - Eats things, big, small, living, dead, never-been-alive. Rather destructive.
Wrath - He would probably go into a rage and want to kill anything on sight. Also, very destructive.
Pride - Would probably be standing in front of the nearest reflective surface saying how wonderful he is and wondering how the hell he's so good, ignoring anything and everything else.
Sloth - Would just sit/lay there doing nothing, except maybe sleep. She'd never do what you told her to do. She's too lazy.
Envy - Would be just plain angry at everyone. He'd be shooting looks of knives at people, maybe even sometimes jumping them, clonking them over the head and taking their place, only to find out he wants to be someone else more. Not very reliable.
Greed - Would be trying to steal EVERYTHING from staplers from the office to money from the bank to clothes off of peoples backs. He might even try and steal your "Master Plan X file" from you!
Lust - Would probably be helping Greed steal her clothes while trying to suck his face, among other things.
I've been meanign to post this for aaages...