What are the bad qualities of Piggy in Lord of the Flies?Why wouldn't he succeed if he became a leader?

Two negative adjectives that come to mind when thinking
about the character of Piggy are "weak" and "whiny."  He is physically out of shape and
struggles to even walk through the creepers and keep up with the other boys, and then he
whines about how is asthma is troubling him.  He may be smart and practical: for
example, his recognizing the usefulness of the conch as a tool to call everyone and
later as a symbol of authority; but he doesn't have the physical presense of Ralph or
Jack that comes with age and experience.  He will not be successful because there are
other boys who inspire confidence with their mere presense, and especially at the start
of the novel, the little boys are in shock and are going to be drawn to an adult
figure.  Piggy's behavior and attidude seem childish, especially to the little
children.  Even Ralph, who does appreciate him, gets annoyed by him as
well.

As the novel progresses, both Jack and Ralph solidify
their positions as leaders of their prospective groups.  There is no chance that Piggy
is going to be able unseat either of them -- especially as Jack becomes more fierce and
powerful.  I would also add that Piggy doesn't truly want to be the
leader, so his lack of drive wouldn't inspire anyone to follow him or even take him all
the seriously, especially by the end of the novel when he nearly blind and seriously
weakened.