This page details the series of steps the game takes when handling each turn of a Pokémon battle.
The phases of a turn are: use of items (with the Bag command); voluntary switching; use of attacks; and end of turn. At the beginning of the turn, the menu of commands appears with "Fight", "Pokémon", "Pack", and "Run."
After both Pokémon choose an attack the attack initiative (who gets to use the attack first) is determined. All attacks are categorized in four priority levels:
2: Endure, Protect, Detect -> 1: Quick Attack, Mach Punch, Extremespeed -> 0: All other attacks -> -1: Counter, Mirror Coat, Whirlwind, Roar, Vital Throw
This process is followed to calculate a Pokémon's Speed in battle. These calculations are done in advance rather than when determining turn order.
After the initiative is determined, the following steps are taken for each Pokémon about to use an attack.
If the Pokémon flinches and isn't asleep or frozen, it skips its attack.
If the Pokémon used Hyper Beam on its previous turn, it "must recharge" and skips its attack. (If the Pokémon also flinches, the "X must recharge!" message isn't shown but Hyper Beam's effect will still end.)
Then, the game checks to see if the attacker is asleep. If so, the attack is not executed unless either Snore or Sleep Talk was chosen.
Next, if Pokémon is asleep ("[Name] is fast asleep!") the game checks if the Pokémon has waken up. If the Pokémon is frozen, the Pokémon won't use the attack unless it's Flame Wheel or Sacred Fire (not even on the second attack turn of Fly, Dig, and so on).
In a battle in which Exp. Points can be gained, only after choosing an attack, the game checks to see if the Pokémon is of a different ID from that of the player. (The OT name is not considered.) If so, the following process is used:
"[Name] used [Attack]!"
If, as commands were chosen, there is no PP remaining for all moves ("There's no PP left for this move!"), the move Struggle is used instead. Otherwise, the move's PP is reduced by 1. If the PP can't be reduced this way, the Pokémon doesn't use that move instead. Fly, Dig, Petal Dance, Thrash, Rollout, and the like use up 1 PP only when selected. If a different attack is used because of disobedience, 1 PP is spent for the attack actually used.
The method for determining a critical hit is below.
After that, the damage is calculated. This is the damage calculation process for the second generation. The game performs each step in the following order.
int(int(int(2×L ÷ 5+2)×A×P ÷ D)/50)
Stat stages refer to levels that increase or decrease stats during a battle. Each stat stage has 13 different levels.
Stat Stage | -6 | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Stat Multiplier | 2/8 | 2/7 | 2/6 | 2/5 | 2/4 | 2/3 | 2/2 | 3/2 | 4/2 | 5/2 | 6/2 | 7/2 | 8/2 |
That stat scale applies to the stat stages for Attack, Defense, Special Attack, Special Defense, and Speed. At the start of a battle, each Pokémon's stat stages begin at 0. The stat stages for a Pokémon are reset to 0 when the Pokémon leaves the battle, (except Baton Pass).
Each stat stage can't go lower than -6 or higher than 6. To apply those stat stages, multiply the stat by the stat multiplier for the corresponding stat stage, then adjust the stat so that it's neither less than 1 nor greater than 999.
The term "stat stages" refers to those for Attack, Defense, Special Attack, Special Defense, and Speed, as well as those for Evasion and Accuracy (see the "Accuracy Check" section, below).
Attack types are the rows; Pokémon types are the columns.
Attack Type | NOR | FIG | FLY | POI | GRO | ROC | BUG | GHO | STE | FIR | WAT | GRA | ELE | PSY | ICE | DRA | DAR |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
NORMAL | 1x | 1x | 1x | 1x | 1x | 1/2 | 1x | 0 | 1/2 | 1x | 1x | 1x | 1x | 1x | 1x | 1x | 1x |
FIGHTING | 2x | 1x | 1/2 | 1/2 | 1x | 2x | 1/2 | 0 | 2x | 1x | 1x | 1x | 1x | 1/2 | 2x | 1x | 2x |
FLYING | 1x | 2x | 1x | 1x | 1x | 1/2 | 2x | 1x | 1/2 | 1x | 1x | 2x | 1/2 | 1x | 1x | 1x | 1x |
POISON | 1x | 1x | 1x | 1/2 | 1/2 | 1/2 | 1x | 1/2 | 0 | 1x | 1x | 2x | 1x | 1x | 1x | 1x | 1x |
GROUND | 1x | 1x | 0 | 2x | 1x | 2x | 1/2 | 1x | 2x | 2x | 1x | 1/2 | 2x | 1x | 1x | 1x | 1x |
ROCK | 1x | 1/2 | 2x | 1x | 1/2 | 1x | 2x | 1x | 1/2 | 2x | 1x | 1x | 1x | 1x | 2x | 1x | 1x |
BUG | 1x | 1/2 | 1/2 | 1/2 | 1x | 1x | 1x | 1/2 | 1/2 | 1/2 | 1x | 2x | 1x | 2x | 1x | 1x | 2x |
GHOST | 0 | 1x | 1x | 1x | 1x | 1x | 1x | 2x | 1/2 | 1x | 1x | 1x | 1x | 2x | 1x | 1x | 1/2 |
STEEL | 1x | 1x | 1x | 1x | 1x | 2x | 1x | 1x | 1/2 | 1/2 | 1/2 | 1x | 1/2 | 1x | 2x | 1x | 1x |
FIRE | 1x | 1x | 1x | 1x | 1x | 1/2 | 2x | 1x | 2x | 1/2 | 1/2 | 2x | 1x | 1x | 2x | 1/2 | 1x |
WATER | 1x | 1x | 1x | 1x | 2x | 2x | 1x | 1x | 1x | 2x | 1/2 | 1/2 | 1x | 1x | 1x | 1/2 | 1x |
GRASS | 1x | 1x | 1/2 | 1/2 | 2x | 2x | 1/2 | 1x | 1/2 | 1/2 | 2x | 1/2 | 1x | 1x | 1x | 1/2 | 1x |
ELECTRIC | 1x | 1x | 2x | 1x | 0 | 1x | 1x | 1x | 1x | 1x | 2x | 1/2 | 1/2 | 1x | 1x | 1/2 | 1x |
PSYCHIC | 1x | 2x | 1x | 2x | 1x | 1x | 1x | 1x | 1/2 | 1x | 1x | 1x | 1x | 1/2 | 1x | 1x | 0 |
ICE | 1x | 1x | 2x | 1x | 2x | 1x | 1x | 1x | 1/2 | 1/2 | 1/2 | 2x | 1x | 1x | 1/2 | 2x | 1x |
DRAGON | 1x | 1x | 1x | 1x | 1x | 1x | 1x | 1x | 1/2 | 1x | 1x | 1x | 1x | 1x | 1x | 2x | 1x |
DARK | 1x | 1/2 | 1x | 1x | 1x | 1x | 1x | 2x | 1/2 | 1x | 1x | 1x | 1x | 2x | 1x | 1x | 1/2 |
The following situations are checked in order. Earlier effects take precedence over later effects.
Then, the accuracy rate is decided as follows. Each Pokémon has one stat stage each for evasion and accuracy, which are not really stats, but affect an attack's probability of hitting an opposing Pokémon. The table below shows the multipliers for evasion and accuracy.
Stat Stage | -6 | -5 | -4 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Accuracy Multiplier | 0.33 | 0.36 | 0.43 | 0.5 | 0.6 | 0.75 | 1 | 1.33 | 1.66 | 2 | 2.33 | 2.66 | 3 |
Evasion Multiplier | 3 | 2.66 | 2.33 | 2 | 1.33 | 1.66 | 1 | 0.75 | 0.6 | 0.5 | 0.43 | 0.36 | 0.33 |
An attack's accuracy is multiplied by its user's accuracy multiplier, as shown in the table above, but not to less than 1, then multiplied by its the opposing Pokémon's evasion multiplier, as shown in the table above, but not to less than 1 or greater than 255. For certain attacks, if the opposing Pokémon is holding BrightPowder, the accuracy is lowered by 20, but not to less than 0. Then, if the accuracy equals 255, it will hit. Otherwise, the attack will hit if a random number from 0 through 255 is less than its accuracy.
Accuracy and evasion are two of a Pokémon's stat stages. Like other stat stages, each Pokémon begins with a stat stage of 0, and a Pokémon's stat stages are reset to 0 when it leaves the battle (except Baton Pass).
Some attacks can't be evaded and always have the accuracy defined for the attack. No accuracy checks are performed for such attacks.
If the attack has an additional effect such as a stat stage modification or a status problem, the probability of the effect happening is determined in this last step. If a random number from 0 through 255 is less than the attack's additional effect chance, the additional effect will occur. For instance, for Blizzard, there is a 51/256 chance the opposing Pokémon will become frozen. The additional effect won't occur if the opposing Pokémon faints because of damage (even if the attack is Ancientpower), Metal Claw, or Steel Wing.
If an attack is successful (including each hit of a multi-hit attack), the following effects resolve:
The attack process, in its short form, for multi-hit attacks is below.
When a Pokémon enters the battle, the effect of Spikes applies for that Pokémon and faints if it causes the Pokémon to have zero HP. If both sides have Spikes and both Pokémon are switched out, here is what happens:
Leader's Pokémon switches out → Leader's Pokémon loses HP because of Spikes → Other player's Pokémon switches out → Other player's Pokémon loses HP because of Spikes → Pokémon with zero HP faint
After a Pokémon's attack turn, any end-of-attack effects will happen for that Pokémon. These effects happen even if a Pokémon doesn't choose a move for use at the beginning of the attack turn. These effects are, in order:
These effects are invoked at the end of the turn, after all Pokémon take their attack turns. The effects are, in order:
Effects above that apply to both players are resolved leader-first unless noted otherwise.
For Future Sight, Perish Song, and Sandstorm, the game applies the effect to each Pokémon; then each Pokémon with 0 HP faints; then the player's Pokémon gain Exp. Points for fainted opponents if necessary; then new Pokémon in battle are chosen if necessary; then the game is decided.
In a wild battle, if the current Speed of the Pokémon trying to run is equal to or greater than the opposing Pokémon's, running is successful. Otherwise, the formula below is used.
X=int(A*32/B)+(30*C)
where:
If X is greater than 255, running is successful. Otherwise, if a random number from 0 through 255 is less than or equal to X, running is successful. Otherwise, running fails.