Custom Rules

Pokémon Showdown supports custom rules in three ways:

Challenging another user, using the command /challenge USERNAME, FORMAT @@@ RULES
Tournaments, using the command /tour rules RULES (see the Tournament command help)
Custom formats on your side server, by editing config/formats.ts

Bans

Bans are just a - followed by the thing you want to ban.

Individual bans

- Arceus - ban a Pokémon (including all formes)

- Arceus-Flying or - Giratina-Altered - ban a specific Pokémon forme

- Giratina-Base - ban only the base forme of a Pokémon (this always works, in case you forget it's called - Giratina-Altered)

- Baton Pass - ban a move

- move: Metronome - ban a move with an ambiguous name

- Bright Powder - ban an item

- item: Metronome - ban an item with an ambiguous name

Group bans

- OU or - DUU - ban a tier

- CAP or - Mega - ban a pokemon category

- LGPE - ban things only available Let's Ge Pikachu/Eevee

- Past - ban things that only appear in a past generation (such as Berserk Gene in Gen 5, spiky-eared Pichu in Gen 5, or Unown in Gen 8)

- Future - ban things that only appears in a future generation (such as Arceus in Gen 1)

- Custom - ban made-up things other than CAP (such as Magikarp's Revenge, or Staff Bros moves)

- Nonexistent - catch-all to ban all nonexistent Pokémon, items, etc. Includes: - CAP, - Past, - Future, - LGPE

- Unobtainable - ban all things designed never to be released (Pokestars in Gen 5, Eternatus-E, Floette-E)

- Unreleased - ban all things that will probably be released eventually (Venusaur in Gen 8)

- Mythical - ban all Mythical Pokémon (such as Mew, Celebi)

- Restricted Legendary - ban all Restricted Legendary Pokémon (such as Zekrom, Eternatus)

- all items - ban all items

- no item - force every pokemon to hold an item (ban empty item slots)

- all abilities, + No Ability - ban all abilities (No Ability needs to be specifically allowed to allow Pokemon with no abilities)

Complex bans

- Blaziken + Speed Boost - ban a combination of things in a single Pokemon (you can have a Blaziken, and you can have Speed Boost on the same team, but the Blaziken can't have Speed Boost)

- Drizzle ++ Swift Swim - ban a combination of things in a team (if any Pokémon on your team have Drizzle, no Pokémon can have Swift Swim)

Unbans

Unbans are just a + followed by the thing you want to unban.

Syntax is identical to bans, just replace - with +, like:

+ Blaziken - unban a Pokémon

+ Past - unban all past-generation-only things

More specific always trumps less specific:

- all Pokemon, + Uber, - Giratina, + Giratina-Altered - allow only Ubers other than Giratina-Origin

- Nonexistent, + Necturna - don't allow anything from outside the game, except the CAP Necturna

For equally specific rules, the last rule wins:

- Pikachu, - Pikachu, + Pikachu - allow Pikachu

+ Pikachu, - Pikachu, + Pikachu, - Pikachu - ban Pikachu

Restrictions

Some rules act on restricted things, without entirely banning or unbanning them. * is used to mark something that is restricted (it will simultaneously be unbanned).

* Uber, Limit One Restricted - allow at most one Uber-tiered Pokémon on a team

* Restricted Legendary, Limit Two Restricted - allow at most two restricted legendaries on a team

Marking something as restricted with * does nothing by itself, you need to combine it with a rule that affects restricted things, such as Limit One Restricted.

Other examples include:

Cross Evolution: Restricting a species prevents it from being the target of a cross evolution. (Ban a species to prevent it from being the base of a cross evolution.)
Mix and Mega: Restricting a species prevents that Pokémon from holding a mega stone. (Ban a stone to prevent all Pokémon from holding it.)
Inheritance: Restricting a species prevents it from being inherited from. (Ban a species to prevent it from inheriting from another species.)
Trademarked: Restricting a move prevents it from being used as a trademark, but the move can still appear in a moveset.

Restriction rules are used to adjust the behaviour of the above metagames. The syntax is identical to bans, just replace - with *, like:

* Blaziken - restrict a Pokémon

* Uber - restrict a group of Pokémon

* Baton Pass - restrict a move

An unban (+) will remove a restriction.

Whitelisting

Instead of a banlist, you can have a list of allowed things:

- all Pokemon, + Charmander, + Squirtle, + Bulbasaur - allow only Kanto starters

- all moves, + move: Metronome - allow only the move Metronome

- all abilities, + No Ability - ban all abilities

- all items, + item: Metronome - allow only the item Metronome

- all items, - no item, + item: Metronome - force all Pokémon to carry the item Metronome (unlike abilities, - all items does not include not carrying an item)

Legality rules

Custom rules can have more complicated behavior. They can also include other rules.

Obtainability rules

Obtainable - allow only things you can actually get in the game without glitches or hacks. Includes: Obtainable Moves, Obtainable Abilities, Obtainable Formes, Obtainable Misc, -Unreleased, -Unobtainable, -Nonexistent.

Obtainable Moves - allow only moves a pokemon can legitimately learn

Obtainable Abilities - allow only abilities a pokemon can naturally get (by itself, does not check unreleased abilities! use -Unreleased for that)

Obtainable Formes - don't allow starting the battle with formes that normally require an in-battle transformation (like megas) (does not check unreleased/nonexistent formes; use -Nonexistent etc)

Obtainable Misc - allow only legal EVs, IVs, levels, genders, and Hidden Power types

Pokedex rules

Hoenn Pokedex - allow only Pokémon in the Hoenn Pokédex (OR/AS)

Sinnoh Pokedex - allow only Pokémon in the Sinnoh Pokédex (Platinum)

Old Unova Pokedex - allow only Pokémon in the Old Unova Pokédex (B/W)

New Unova Pokedex - allow only Pokémon in the New Unova Pokédex (B2/W2)

Kalos Pokedex - allow only Pokémon in the Kalos Pokédex (X/Y)

Alola Pokedex - allow only Pokémon in the Alola Pokédex (US/UM)

Galar Pokedex - allow only Pokémon in the Galar Pokédex (SW/SH) [Ban Pokémon you can catch in the adventures but are not listed in the Pokédex like Ultra Beasts and Landorus]

Clauses

Species Clause - limit one Pokémon per dex number

Nickname Clause - limit one Pokémon per nickname

Item Clause - no two Pokémon can have the same item

2 Ability Clause - limit two Pokémon with the same ability

OHKO Clause - ban one-hit KO moves (Fissure, Sheer Cold, etc)

Evasion Moves Clause - ban moves that directly boost evasion (Double Team, Minimize)

Evasion Abilities Clause - ban abilities that boost evasion (Sand Veil, Snow Cloak)

Moody Clause - ban the ability Moody

Swagger Clause - ban the move Swagger

CFZ Clause - ban the use of crystal-free Z-Moves (having moves like Devastating Drake hacked directly on the moveset in formats like Hackmons, instead of using Dragon Claw + Dragonium Z)

Z-Move Clause - ban Pokémon from holding Z-Crystals

3 Baton Pass Clause - prevent more than three Pokémon from having Baton Pass on a team

Baton Pass Clause - prevent more than one Pokémon from having Baton Pass, and prevent Pokémon from being capable of passing boosts in Speed and another stat at the same time.

Accuracy Moves Clause - ban moves that have a chance to lower the target's accuracy when used

Same Type Clause - force all Pokémon on a team to share a type with one another

NFE Clause - ban all Pokémon that are not fully evolved (Pokémon can be re-added manually by simply unbanning them)

Forme Clause - limit one of each forme of a Pokémon on a team (a team can have Zamazenta + Zamazenta-Crowned, but not Zamazenta + Zamazenta)

Miscellaneous

Allow AVs - allow Pokémon to have their stats boosted by Awakening Values in Let's Go formats

Allow Tradeback - allow Pokémon in Gen 1 to have moves from their Gen 2 learnsets

STABmons Move Legality - allow Pokémon to have almost any move that matches their typing

Little Cup - allow only Pokémon that can evolve and aren't evolved

Not Fully Evolved - allow only Pokémon that aren't fully evolved

Mimic Glitch - allow Pokémon with access to Assist, Copycat, Metronome, Mimic, or Transform to gain access to almost any other move

Value rules

Certain rules can specify a value.

Max Level = 50 - ban Pokémon above level 50

Min Level = 10 - ban Pokémon below level 10

Max Total Level = 200 - only allow Pokémon whose combined levels add up to 200 or below (if combined with Picked Team Size, only the picked team needs to be below that combined level)

Max Move Count = 5 - you can bring Pokémon with up to 5 moves

Max Team Size = 4 - you must bring a team with at most 4 pokemon (before Team Preview, in games with Team Preview)

Min Team Size = 4 - you must bring a team with at least 4 pokemon (before Team Preview, in games with Team Preview)

Picked Team Size = 4 - in Team Preview, you must pick exactly 4 pokemon (if this exists, Min Team Size will default to this number)

Min Source Gen = 7 - only allow pokemon obtained in this generation or later

Adjust Level = 50 - change all levels to 50, like in some in-game formats (unlike Max Level, this still allows moves learned above level 50)

Adjust Level Down = 50 - change Pokémon with level above 50 to level 50 (but leave Pokémon below 50 alone), like in some in-game formats (unlike Max Level, this still allows moves learned above level 50)

Force Monotype = Water - require all Pokémon to be Water-type

EV Limits = Atk 0-100 / Def 50-150 - require EVs to be in those ranges

In-battle rules

Team Preview - use Team Preview

Blitz - use the Blitz timer (30 second Team Preview, 10 seconds per turn)

VGC Timer - use the VGC timer (90 second Team Preview, 7 minutes Your Time, 1 minute per turn)

Mega Rayquaza Clause - prevent Rayquaza from Mega Evolving

Sleep Clause Mod - prevent Pokémon from falling asleep if they have sleeping allies

Freeze Clause Mod - prevent Pokémon from getting frozen if they have frozen allies

Cancel Mod - show the Cancel button and allow players to cancel their moves

Inverse Mod - inverse type effectiveness (like in Gen 6 Inverse Battles)

Scalemons Mod - Pokemon will have their base stats, barring HP, adjusted to make their BST as close to 600 as possible (in Gen 1, BSTs will be scaled to 500)

Gen 8 Camomons - Pokémon will change their typing to match their first two moveslots

Gen 7 Tier Shift - Pokémon will have higher base stats the lower their Gen 7 Smogon tier is

Dynamax Clause - prevent Pokémon from Dynamaxing during battle. Cannot be used to allow Dynamaxing in old gens

Endless Battle Clause - prevent battles from proceeding endlessly

HP Percentage Mod - Show the opposing Pokémon's HP rounded to the nearest percent, as opposed to a range of percentages based upon the health bar's size in-game

Exact HP Mod - Show all Pokémon's exact HP and max HP in the battle log

Switch Priority Clause Mod - make the fastest Pokémon switch first when more than one Pokémon switches out at once, unlike in Emerald link battles, where Player 1's Pokémon would switch first.

Standard Rulesets

Note: Most formats already come with one standard ruleset. Removing and adding multiple standard rulesets in the same tournament is likely to have unintended results.

Standard - the standard ruleset for most Smogon singles formats. Includes the Evasion Moves Clause, Sleep Clause Mod, Species Clause, Nickname Clause, OHKO Clause, Endless Battle Clause, HP Percentage Mod, and Cancel Mod.

Standard NEXT - the standard ruleset for NEXT. Allows some unreleased Pokémon and includes the Evasion Moves Clause, Nickname Clause, Sleep Clause Mod, Species Clause, OHKO Clause, HP Percentage Mod, and Cancel Mod. Bans Soul Dew.

Flat Rules - the standard ruleset for in-game formats, such as Battle Spot. Includes Species Clause, Item Clause, Cancel Mod, Nickname Clause, and Team Preview. Bans mythical Pokémon and restricted legendaries (e.g. Zekrom, Reshiram, Zygarde, Eternatus)

Standard NatDex - the standard ruleset for National Dex formats. Allows the National Dex. Includes Nickname Clause, HP Percentage Mod, Cancel Mod, Endless Battle Clause.

Standard Doubles - the standard ruleset for most Smogon doubles formats. Includes Species Clause, Nickname Clause, OHKO Clause, Evasion Abilities Clause, Evasion Moves Clause, Endless Battle Clause, HP Percentage Mod, Cancel Mod.

Removing rules

Put ! in front of a rule to remove it, like:

! Team Preview - do not use Team Preview

You can use this to remove individual parts of rules, like:

Obtainable, ! Obtainable Moves - require pokemon to be obtained legitimately, except for moves, which they can use whatever

For value rules, you just put ! in front of the rule name, no =:

Flat Rules, ! Picked Team Size - use Flat Rules, but players can pick 6

To prevent mistakes, value rules can't be changed without being removed first. Use !! to remove and replace a value rule:

Flat Rules, !! Picked Team Size = 5 - use Flat Rules, but players can pick 5

Multiple rules

In case you haven't figured it out from the rest of this page, you combine rules with a , (comma).

Tiers and Formats

Any format (starting with Gen [number]) can be used as a rule, to add all rules from that format.

For example:

Gen 8 OU - add all clauses and bans from Gen 8 OU.

Gen 8 Almost Any Ability - add all clauses and bans from Gen 8 Almost Any Ability, allowing Pokémon to use almost any ability in the game.

People often use "tier" to mean "format", but in rulesets, the difference is important. A format is a list of rules for a game you can play, such as "Gen 8 OU". A tier is a list of Pokémon which can be banned or unbanned, such as "OU".

- OU, + Ubers - ban all Pokémon currently in OU and unban all Pokémon currently in Ubers