This is confusing.
 I
If you are using Ditto, and attack with Drag Off, what happens?
 
Using Drag Off counts as your attack.  The card says before doing damage, choose 1 of your opponenet's benched pokemon and switch it with the defending pokemon.  Then, do the damage to the new defending pokemon.
 
But, when you switch, DItto should become the new defender.  If the new defender was, anyone but Dark Machoke, that would make DItto someone else who does not have the Drag off attack.
 
That being the case, how does ditto finish the attack?
 
My feeling is that the benched pokemon suffers damage during the act of being dragged, so, in this case, Eevee will take 40 damage.  (Fighting weakness.)
 
Others think that this ends up being a "Gust-of-Wind" atack with no damage.
 
Help!
 
Chris

Wonderful question.  The answer is a little weird, but here goes:

Once an attack begins, nothing from the outside can interfere with the attack unless something very specific (such as Smokescreen) says it can.  This includes Ditto's Transform Pokemon Power.  Ditto will actually remain a Machoke long enough to do damage to the defending Pokemon.  Immediately afterwards, it will realize it is no longer a Machoke and transform to the new Pokemon.

Thanks for the good question.

Scott