Swords Dance
increases your Pokémon's Attack statistic by an amount equal to its
initial value. Thus, the first use of this attack results in double the
normal Attack score. The second use results in triple the normal Attack
score, while the third use results in quadruple the normal Attack score.
Effects are cumulative for a maximum of three uses. Further uses have no
effect.
Note that like other statistics, Attack has a maximum value of 999. If
a use of this attack would raise your Pokémon's Attack score beyond 999,
it will instead raise it only to that value. If its Attack score has
already reached 999, this attack will fail.
Also note that since the attacker's Attack statistic is being 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.