Timing Notes

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This page details the series of steps the game takes when handling each turn of a Pokémon battle.

Content

Round phases

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."

Fight: Choose a move from the list of moves that appears. This move chosen is called the move "chosen for use" for this turn.
Pokémon: Check data on Pokémon or switch the Pokémon in battle. Switching is not usable if a Pokémon "can't switch out" because of a move's effect.
Pack: Use an item on the Pokémon in battle, who skips its attack this turn.
Run: Attempt to run from a wild Pokémon battle. See the Chance of Running in Wild Battles section, below, for how the game calculates the escape rate.

Priority

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

The attack with the higher priority strikes first.
If both attacks have the same priority, the holder of Quick Claw has a 23.4% chance of striking first,. If this chance succeeds and both Pokémon hold a Quick Claw, the one who strikes first is randomly determined (in battles in which Exp. Points can be gained, the player's Pokémon always strikes first in this case).
Otherwise, the Pokémon with the higher Speed strikes first.
If both Pokémon have the same Speed, the one who strikes first is randomly determined.

Calculating Speed

This process is followed to calculate a Pokémon's Speed in battle. These calculations are done in advance rather than when determining turn order.

Multiply the Speed by the Speed multiplier derived from the Pokémon's Speed stat stage.
In a battle in which Exp. Points can be gained, if the Pokémon is controlled by the player and the player has earned the Plain Badge, the Speed is raised by 1/8 of its previous value.
If the Pokémon is paralyzed, divide the Speed by 4.

For the purposes of Detect, Endure, and Protect, Pokémon who chose to switch at the beginning of a turn are ignored when determining whether a particular Pokémon "strikes last" in that turn.

Process

After the initiative is determined, the following steps are taken for each Pokémon about to use an attack.

First checks

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.)

Sleep and Freeze Checks

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).

Other Pre-Attack Checks

If the attacker is confused, there is a 50% chance for the attacker to hit itself instead.
If the attacker is in love, there is a 50% chance for the attack to be canceled.
The attacker can't use the move if it can't be used because of Disable.
If the attacker is paralyzed, there is a 50% chance for the attacker to be unable to move.
Obedience check, see below.

Obedience check

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:

The badge level (B) is determined based on the player's Badges.
- If the player has no Badges, B is 10.
- If the player has the Hive Badge, B is 30.
- If the player has the Fog Badge, B is 50.
- If the player has the Storm Badge, B is 70.
- If the player has the Rising Badge, B is 101.
If the Pokémon's level (L) is greater than B and a random number from 0 through (L + B - 1) is greater than or equal to B and the Pokémon is attempting to use a move, the Pokémon becomes disobedient. When disobedient, the Pokémon no longer has a move it last used, Encore ends against the Pokémon, and one of the following happens:
- If the Pokémon would use Snore or Sleep Talk while it's asleep, the Pokémon instead "ignore[s] orders sleeping".
- Otherwise, if another random number from 0 through (L + B - 1) is greater than or equal to B:
  - C is set to N - (L - B), where N is a random number from 0 through 255.
  - If C is 0 or greater and is greater than or equal to L minus B, one of the following messages is used: "X is loafing around", "X ignored orders!", "X turned away!", "X won't obey!"
  - If C is 0 or greater and is less than L minus B, the message shown is "X won't obey!" and the Pokémon deals confusion damage to itself.
  - If C is less than 0, the message shown is "X began to nap!" and the Pokémon goes to sleep. (Not prevented by Safeguard or Substitute.)
- Otherwise, the Pokémon will attempt to use a different move if possible. (It could not use a different move while asleep, during the effect of Disable, or if the different move has zero PP, but it could while frozen, even if the different move isn't Flame Wheel or Sacred Fire.) If it can't, one of the following messages is used: "X is loafing around", "X ignored orders!", "X turned away!", "X won't obey!" If the Pokémon uses a different move, the last move it used is not set to that move, the last move it chose for use is set to that move, and PP is reduced from that different move instead of from the move ordered.

An obedience check is done even if the Pokémon uses Pursuit as the opposing Pokémon is about to switch. An obedience check is not done if the Pokémon is continuing to use Thrash, Petal Dance, Outrage, Bide, Rollout, or a two-turn attack during their effects.

Attacker uses the attack

"[Name] used [Attack]!"

Check PP (Power Points)

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.

Is it a critical hit?

The method for determining a critical hit is below.

Set C to 0.
If Focus Energy is in effect for attacker, add 1 to C.
If attack is Aero Blast, Crab Hammer, Cross Chop, Karate Chop, Razor Leaf, or Slash, add 2 to C.
If attacker is holding Scope Lens, add 1 to C.
If attacker's current species is Chansey and the attacker is holding Lucky Punch, C is set to 2.
If attacker's current species is Farfetch'd and the attacker is holding Stick, C is set to 2.
The critical hit ratio is as follows:
- C = 0: 17/256
- C = 1: 32/256
- C = 2: 64/256
- C = 3: 85/256
- C = 4 or more: 128/256

A critical hit deals two times more damage than usual (see below). Also during a critical hit, if the attacker's Attack or Special Attack stat stage is equal to or less than the opposing Pokémon's Attack or Special Defense stat stage, changes to Attack, Defense, Special Attack, and Special Defense because of Reflect, Light Screen, badges, stat stages, and burns are ignored.

Damage Calculation

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.

In battles in which Exp. Points can be gained, the badges have the appropriate stat multiplied by 9 and divided by 8 for Pokémon controlled by the player (the Zephyr Badge raises Attack, the Plain Badge raises Speed, the Mineral Badge raises Defense, and the Glacier Badge raises Special Attack).* (This calculation is done in advance rather than during damage calculation.)
Stat stage modifying attacks (see below) modify the appropriate stat (Attack or Defense).* (This calculation is done in advance rather than during damage calculation.)
If the attacker is burned, halve the Attack value.* (This calculation is done in advance rather than during damage calculation.)
If the attack is Selfdestruct or Explosion, divide the opposing Pokémon's Defense by 2.
If Reflect is in effect for the opposing Pokémon, double the Defense value.*
If Light Screen is in effect for the opposing Pokémon, double the Special Defense value.*
If the attacker's original species is Pikachu and the attacker is holding Light Ball, Special Attack is doubled.
If the attacker's original species is Cubone or Marowak and the attacker is holding Thick Club, Attack is doubled.
If the Attack or Special Attack stat, the Defense or Special Defense stat, or both exceeds 255, divide both stats by 4 (In Gold/Silver/Crystal, the result is then truncated to an 8-bit integer; for example, 0x0123 in hexadecimal becomes 0x0023).
If the opposing Pokémon's original species is Ditto and the opposing Pokémon is holding Metal Powder, both Defense and Special Defense are multiplied by 1.5.
If the Attack or Special Attack stat, the Defense or Special Defense stat, or both is 0, it becomes 1.
The damage is equal to:
int(int(int(2×L ÷ 5+2)×A×P ÷ D)/50)
where L is the attacker's level, A is the attacker's Attack or Special Attack value, P is the attack's power, and D is the opposing Pokémon's Attack or Special Defense value. For physical attack types (Normal, Fighting, Flying, Poison, Ground, Rock, Bug, Ghost, Steel), use the Attack and Defense values. For special attack types (Fire, Water, Electric, Grass, Ice, Psychic, Dragon, Dark), use the Special Attack and Special Defense values.
When the attack does a critical hit (see above), the calculated damage is doubled.
If the attacker is holding certain items like Pink Bow and Charcoal, multiply the calculated damage by 1.1 (multiply by 110, divide by 100) if the attacker is using an attack of the appropriate type.
If the damage calculated is greater than 997, it becomes 997.
Add 2 to the calculated damage.
Weather. Sunny Day raises the damage of Fire-type attacks by 50% and lowers the damage of Water-type attacks by 50%. Rain Dance raises the damage of Water-type attacks by 50%, lowers the damage of Fire-type attacks by 50%, and halves the damage done by Solarbeam.
Badges. In the Gold/Silver/Crystal version, in battles in which Exp. Points can be gained, the Johto and Kanto badges multiply damage of the appropriate attack type by 9/8 for Pokémon controlled by the player, as shown here: Zephyr Badge: Flying; Hive Badge: Bug; Plain Badge: Normal; Mineral Badge: Steel; Glacier Badge: Ice; Fog Badge: Ghost; Storm Badge: Fighting; Rising Badge: Dragon; Soul Badge: Poison; Volcano Badge: Fire; Boulder Badge: Rock; Rainbow Badge: Grass; Marsh Badge: Psychic; Earth Badge: Ground; Thunder Badge: Electric; Cascade Badge: Water.
Same Type Attack Bonus. If the attack type shares a type with one of the user's types, the damage is multiplied by 1.5.
Types of attacker and defender. The damage calculated is multiplied by a multiplier that depends on the attacker's and the opposing Pokémon's types (see the Type Matchup Chart, below). As an exception, after Foresight is used against the opposing Pokémon, normal and fighting attacks against the opposing Pokémon are normally effective against the Ghost type.
Finally, in a process called "damage variance", a random number from 217 through 255 is multiplied in the currently calculated damage, and divided by 255.

* This effect is ignored if the attack does a critical hit and the attacker's Attack or Special Attack stat stage is less than or equal to the opposing Pokémon's Attack or Special Defense stat stage.

Stat Stages

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).

Type Matchup Chart

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

Accuracy

The following situations are checked in order. Earlier effects take precedence over later effects.

Using Dream Eater when the opposing Pokémon is not sleeping will fail.
If the opposing Pokémon had used Protect or Detect, attack will fail.
If attacker had used Mind Reader or Lock-on, attack won't hit Pokémon using Fly if attack is Earthquake, Fissure, or Magnitude, or the attack will succeed otherwise (Gust, Thunder, Twister, and Whirlwind will be effective even to opponents using Dig). Either way, the effect of Mind Reader and Lock-on now ends.
Absorb, Dream Eater, Giga Drain, Leech Life, and Mega Drain on a substitute will fail.
Gust, Thunder, Twister, and Whirlwind are effective to Pokémon using Fissure, Fly; Earthquake, and Magnitude are effective to Pokémon using Dig. All other attacks will fail in either case.
During Rain Dance, Thunder won't miss.
Swift won't miss.

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.

Additional Effects

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.

Attack Effects

If an attack is successful (including each hit of a multi-hit attack), the following effects resolve:

Recoil/Drain
Additional effect if the opposing Pokémon doesn't have zero HP
The opposing Pokémon faints if it has zero HP
Destiny Bond/Rage effect
Defrost check

Multi-hit attacks

The attack process, in its short form, for multi-hit attacks is below.

Check accuracy and success
For each hit:
1. Calculate damage
2. Stop multi-hit attack if the opposing Pokémon fainted
Check for additional effect

Switching Out

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

End of attack

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:

HP loss from poison/burn
HP loss and recovery from Leech Seed
Effect of Nightmare
Effect of Curse

End of turn

These effects are invoked at the end of the turn, after all Pokémon take their attack turns. The effects are, in order:

Future Sight (non-leader first)
Sandstorm/Sunny Day/Rain Dance
Multi-turn attacks
Perish Song
Recover with Leftovers
Check if defrosted
Check end of Reflect/Light Screen/Safeguard
Check for condition based on Berry
Check end of Encore

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.

Chance of Running in Wild Battles

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:

A = Current Speed of Pokémon trying to run
B = Remainder of (D / 4) divided by 256 where D is the current Speed of the opposing Pokémon. If B equals 0, running is successful.
C = Number of times the player already tried to run this battle, not counting the current attempt. Doesn't count attempts to run when an effect (such as Mean Look) prevents the Pokémon from running. This variable is reset to 0 when the player chooses the Fight command, but doesn't change when the player's Pokémon changes.

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.

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