Deals more damage when the user has less HP remaining, with a maximum of 200 power.

Reversal deals damage. The power is increased when the user's HP is lower.
On a technical level, the damage calculation works by multiplying the current HP% with a base multiplier and grouping the result in ranges, but for practical purposes this can be ignored.
The following table shows the power and HP thresholds:

Power	% of maximum HP
20	above 68.75%
40	between 68.75% and 35.42%
80	between 35.42% and 20.83%
100	between 20.83% and 10.42%
150	between 10.42% and 4.17%
200	below 4.17%

• In Gen 2 Reversal can not cause critical hit and is not varied by a random factor during damage calculation.
• In Gen 4 the HP calculation is slightly different:
  The table below shows the exact amounts:

  Power	% of maximum HP
  20	above 67.19%
  40	between 67.19% and 34.38%
  80	between 34.38% and 20.31%
  100	between 20.31% and 9.38%
  150	between 9.38% and 3.13%
  200	below 3.13%