While in battle, all stats (except HP) can be increased and decreased with certain Attacks. Each stat can be increased up to six times or decreased up to six times. If one Pokemon’s stat is increased to the max, it can then be reduced up to twelve times to reach the bare minimum. Base Stats and Battle Stat modifications are a bit different from each other.
Base Stat Modifications
Base stats can be increased or decreased a max of six stages with stat altering moves or items. Some stat changing moves can alter a Pokemon’s stats two stages at a time, meaning they only have to be used three times instead of six.
The following tables showcase the increases and decreases made to base stats. Say an attack does 50 points of damage. If you increase a stat that affects that damage by three stages, you will increase the damage by 150%, adding 75 points to the 50 points of damage, making it a total of 125 damage. Some people find it easier to use damage multipliers by multiplying 50 by 2.5x to get 125 damage, so those are included as well.
Battle Stat Modifications
Unlike base stats, accuracy and evasion changes have slightly different values. The principles are the same, and you can increase or decrease the stats by six stages, but the percentage they’re increased or decreased by is slightly altered.
Accuracy Increase / Evasion Decrease
Accuracy Decrease / Evasion Increase