Date-Based Events

Date-based events are in-game events triggered only on specific dates. Unlike Mystery Gifts, these events are specifically triggered by time checks within the game's script. They can occur each year within their specified date range unless they're either set to run on specific years or removed from the game in a future update.

April Fools

First noticed in 2019, Pokémon Sardonyx contains a minor change that occurs on April Fools Day. During this day, certain Gen 1 Pokémon will have their name altered upon creation. A number of these reflect their beta names. These Pokémon obtained by the player can still have their name changed via the Name Rater in Citrivale City. This change originally lasted from April 1 to April 14 before being shortened to just April 1.

Pokémon		New Name
	Kakuna	Kokoon
	Pidgey	Pidge
	Pidgeotto	Pidgeot
	Rattata	Rattatak
	Ekans	Arbo / Nagahis
	Arbok	Nagaasp
	Sandslash	Sandstorm
	Clefairy	Aria
	Clefable	Ariala
	Vulpix	Foxfire
	Ninetales	Ninetai
	Jigglypuff	Pudding
	Wigglytuff	Custard
	Oddish	Ladish
	Paras	Parasyte
	Diglett	Digda
	Growlithe	Flamie
	Arcanine	Arcanine
	Poliwag	Aqua
	Poliwhirl	Aquanau
	Poliwrath	Aquamar
	Abra	Hocus
	Kadabra	Pocus
	Machop	Kara-tee
	Machoke	Kung-foo
	Machamp	Ju-doh
	Tentacool	Jilly
	Tentacruel	Man O War
	Rapidash	Gallop
	Slowpoke	Slowmo
	Magnemite	Coil
	Magneton	Recoil
	Farfetch'd	Fowler
	Doduo	Dodo
	Dewgong	Manaty
	Gastly	Spirit
	Haunter	Spectre
	Gengar	Phantom
	Drowzee	Sleeper
	Kingler	Kingle
	Exeggcute	Eggstre
	Exeggutor	Eggscut
	Cubone	Orphon
	Marowak	Guardia
	Hitmonlee	Lee
	Hitmonchan	Chan
	Lickitung	Tonguetyd
	Koffing	Ny
	Weezing	La
	Chansey	Lucky
	Tanegla	Meduza / Medusa
	Goldeen	Goldy
	Seaking	Neptune
	Scyther	Stryke
	Gyarados	Skulkraken
	Lapras	Ness
	Ditto	Morpho
	Eevee	Eon
	Porygon	Poregon
	Omanyte	Ess
	Omastar	Kargo
	Kabuto	Att
	Kabutops	Lantis
	Aerodactyl	Ptera
	Dratini	Dragoon
	Dragonair	Dragyn

October

First witnessed in versions 2.1 to 2.2.2, Pokémon Sardonyx contains a few minor changes lasting through the entire month of October.

• Pokémon encountered in the wild have a 10% chance of becoming one of several Ghost-type Pokémon in the event that they would otherwise not be Ghost-type.
• Phantump and Pumpkaboo can be found lurking in Peridot Forest. Each map contains one of the two. After an encounter, they will disappear and respawn after a week. This allows for a maximum of 5 encounters with each map for a total of 20 throughout the month.
• Specific sand castles in Citrivale Docks, Amaris City, and Ironis City will be revealed to be Sandygast. After an encounter, they will disappear and respawn after a week. This allows for a maximum of 5 encounters with each map for a total of 15 throughout the month.
• The power of Ghost- and Dark-type moves are increased by 30%.

Ghost-Type Pokémon Spawning

During the month of October, there is a 5% chance of the player encountering Ghost-type Pokémon rather than a Pokémon they would normally encounter if it is not already a Ghost-type. The way what Pokémon is encountered is determined as followed:

The game creates four slots. Two are filled by Duskull and Yamask. The other two are left blank. The game then uses the original Pokémon's type to attempt to fill in these two slots.

• Litwick if the Pokémon is Fire-type
• Frillish if the Pokémon is Water-type
• Drifloon if the Pokémon is Flying-type
• Golett if the Pokémon is Ground-type
• Gastly if the Pokémon is Poison-type
• Sableye if the Pokémon is Dark-type

Dual-types are taken into account. If the Pokémon is a single type, the remaining slot is filled by Shuppet. If the Pokémon is none of those types, the slots are filled up by Misdreavus and Shuppet. The Ghost-type Pokémon encountered is then randomly chosen from the four resulting options.

For instance, if the player would have normally encountered an Altaran Growlithe and this occured, they would instead encounter a Litwick, Frillish, Duskull, or Yamask.

There are a few exceptions to this:

• The starter Pokémon the player catches
• The Alolan Raticate found in Sidequest: Pest Extermination