Acid causes damage and has a 10% chance of lowering the enemy's
Defense.
Note that since the victim's Defense statistic is altered, only the
effectiveness of Physical attacks, such as Hyper Beam and Sludge, will be increased. Damage caused by
Special attacks like Ice Beam and Flamethrower will not be affected.
For more information on the different kinds of attacks and how damage
is determined for each of them, see the Attack Base Explanation.