What does everyone see in Ditto? Here are the
  interesting points I found in using Ditto:
   
  (1) If Ditto Transforms into a Poke'mon with less
  HP than Ditto has damage, it will instantly gets KO'ed!!
  Let me explain. Ditto Transforms with 40 damage
  (on the verge of fainting, I know,)
   into a Base Set Abra, or a Rattata, or a Lt
  .Surge's Magnemite, etc. These Poke'mon only have 30 HP, so Ditto will be
  instantly KO'ed because it had 4 Damage counters on it, and it Transformed
  into a Poke'mon with 30 HP. A player must be wary to never do this.
   
  (2) Ditto is extremely vurnerable when a Muk is in
  play. It can't defend itself because its Poke'mon Power is the second
  best thing it has (Psychic Resistance being the best). I take every
  advantage of this moment when this occurs. Gust of Wind Ditto from the Bench,
  Low Kick with Machop with PlusPower. That's it for Ditto.
   
  (3) Ditto is also extremely vurnerable when
  it is Asleep, Confused, or Paralyzed.
   
  One more thing. Observation #1 would say(common
  sense has to be employed here) that Ditto can also transform into a Mysterious
  Fossil!!!!!!! I take every advantage of this moment when it occurs as well.
  Transforming into a Mysterious Fossil means that 'Ditto' can't attack or
  retreat. It'll get Ko'ed by any attack that does damage! The only thing it
  will be able to do is to discard itself!! Your opponent can't even retreat
  Ditto!!!
   
  Right. Anyway, I know how to use Ditto, mind you.
  Just not as good as other people. Somehow, Ditto has more to it than meets the
  eye.
   
  UltraMaster64