theSLAYER

After the player captures Regirock, Regice and Registeel at their individual ruins in the Crown Tundra, the player can go to the Split-Decision Ruins and choose to encounter either Regieleki or Regidrago. The choice is made by illuminating the floor tiles to match the design of the dots on the wanted golem's face. Once the choice has been made, the decision cannot be undone, even if the chosen Regi has yet to be caught.
In order to open the door to enter the ruins, the first requirement is to have players capture Regirock, Regice and Registeel on that save. The second requirement is for Regirock, Regice and Registeel to be in the player's party while interacting with the door. These 3 can be of any origin (doesn't matter if transferred from HOME or caught in Crown Tundra).

 
 

Through the narrative of the story, the player battles Glastrier once, but is unable to capture it.
Instead, the player catches a Rider Calyrex (a Calyrex fused with Glastrier or Spectrier).
Glastrier can be obtained by unfusing the Ice Rider Calyrex that was caught.

Whether Calyrex is fused with Glastrier or Spectrier, depends on the choice the player made during the story.

Through the narrative of the story, the player battles Calyrex once, but is unable to capture it.

In the Crown Shrine, Calyrex will fuse with either a Spectrier or Glastrier (depends on the player's choice). Base form Calyrex can be obtained by unfusing the Rider Calyrex that was caught.

Through the narrative of the story, the player battles Spectrier once, but is unable to capture it.
Instead, the player catches a Rider Calyrex (a Calyrex fused with Glastrier or Spectrier).
Spectrier can be obtained by unfusing the Shadow Rider Calyrex that was caught.

Whether Calyrex is fused with Glastrier or Spectrier, depends on the choice the player made during the story.

After the player captures Regirock, Regice and Registeel at their individual ruins in the Crown Tundra, the player can go to the Split-Decision Ruins and choose to encounter either Regieleki or Regidrago. The choice is made by illuminating the floor tiles to match the design of the dots on the wanted golem's face. Once the choice has been made, the decision cannot be undone, even if the chosen Regi has yet to be caught.
In order to open the door to enter the ruins, the first requirement is to have players capture Regirock, Regice and Registeel on that save. The second requirement is for Regirock, Regice and Registeel to be in the player's party while interacting with the door. These 3 can be of any origin (doesn't matter if transferred from HOME or caught in Crown Tundra).

After the player triggers the roaming event for Galarian Articuno, Galarian Zapdos and Galarian Moltres at the Dyna Trill Hill, the birds will begin roaming.

Galarian Articuno roams along Crown Tundra, Galarian Zapdos roams along the mainland Galar's Wild Area, and Galarian Moltres roams along the Isle of Armor.

After the player triggers the roaming event for Galarian Articuno, Galarian Zapdos and Galarian Moltres at the Dyna Trill Hill, the birds will begin roaming.

Galarian Articuno roams along Crown Tundra, Galarian Zapdos roams along the mainland Galar's Wild Area, and Galarian Moltres roams along the Isle of Armor.

After the player triggers the roaming event for Galarian Articuno, Galarian Zapdos and Galarian Moltres at the Dyna Trill Hill, the birds will begin roaming.

Galarian Articuno roams along Crown Tundra, Galarian Zapdos roams along the mainland Galar's Wild Area, and Galarian Moltres roams along the Isle of Armor.

After the player captures Cobalion, Terrakion, and Virizion in Crown Tundra, and report back to Sonia, and she then proceeds to leave, a new pair of footprints will appear near the cooking pot found at the small island near the Dyna Tree Hill. If the player fulfills 2 requirements, being (a) have the aforementioned 3 in party (can be caught in Crown Tundra or HOME transferred) during (b) cooking curry in camp, a wild Keldeo will appear on that island.
This Keldeo encounter is shiny locked.

After completing the main story of Crown Tundra, the player is able to receive Cosmog from one of the villagers in a house in Freezington. This Cosmog gift is shiny locked.

The conditions for unlocking this gift is presently unclear.
It appears that there's two conditions the player needs to satisfy:
(1) Have 15 successful Dynamax Adventures
(2) Capture at least 4 Ultra Beasts from Dynamax Adventures.
This gift is shiny locked.
At that point, it would appear in the overworld of the Max Lair, and players can receive it.
In order for Ultra Beasts to appear in the Dynamax Adventures, players must complete the story of Crown Tundra.

When players interact with a particular gravestone along the grasslands of Ballimere Lake, the words "let my voice be heard" is etched into it. When the player then goes to talk to 32 players in the vicinity, and the gravestone would then have the text "my voice has been heard".
After that, when the player reloads the area, a Spiritomb will be in the over world awaiting battle.
This encounter can be shiny.

Distribution Title Brrr ! Un Pitrouille ! Wondercard ID 523     PID Cannot Be Shiny Games XY Type Online Wi-Fi Dates Oct 1 -31 2014 Nickname (default) Gender Male/Female Level 50 Nature Random Ability Pickup (1) or
Frisk (2) or
Insomnia (HA) OT Horreur 2014 TID 10014 Location a lovely place Ribbon Event , Ball Cherish Ball Held Item Rocky Helmet Moves Trick-or-Treat Astonish Scary Face Shadow Sneak Relearn
Moves (None) (None) (None) (None) Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Un Magmar ! Wondercard ID 504     PID Cannot Be Shiny Games X Type Serial Code Dates Apr 14 -
Sep 30, 2014 Species Magmar Nickname (default) Gender Male Level 30 Nature Random Ability Vital Spirit (HA) OT PRINT. 2014 TID 4014 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Magmarizer Moves Smokescreen Fire Spin Confuse Ray Fire Punch Relearn
Moves (None) (None) (None) (None) Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Un Élektek ! Wondercard ID 504     PID Cannot Be Shiny Games Y Type Serial Code Dates Apr 14 -
Sep 30, 2014 Species Electabuzz Nickname (default) Gender Male Level 30 Nature Random Ability Vital Spirit (HA) OT PRINT. 2014 TID 4014 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Electirizer Moves Low Kick Shock Wave Light Screen Thunder Punch Relearn
Moves (None) (None) (None) (None) Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Un Prismillon Motif Poké Ball ! Wondercard ID 511     PID Cannot Be Shiny Games XY Type Online+Serial Dates Aug 14 -
Sep 30, 2014 Species Vivillon (Poke Ball Forme) Nickname (default) Gender Male Level 12 Nature Random Ability Shield Dust (1) or Compound Eyes (2) OT ÉTÉ 2014 TID 8134 Location a lovely place Ribbon Classic , Ball Poke Ball Held Item None Moves Stun Spore Gust Light Screen Struggle Bug Relearn
Moves (None) (None) (None) (None) Receiving Text 0x35 Thank you for receiving this distribution! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Un Prismillon Poké Ball ! Wondercard ID 511     PID Cannot Be Shiny Games XY Type Local Wi-Fi Dates Jun 4 -
21, 2014 Species Vivillon
(Poke Ball Forme) Nickname (default) Gender Male Level 12 Nature Random Ability Shield Dust (1) or Compound Eyes (2) OT Paris TID 6014 Location a Pokémon Center Ribbon Classic , Ball Cherish Ball Held Item None Moves Stun Spore Gust Light Screen Struggle Bug Relearn
Moves (None) (None) (None) (None) Receiving Text 0x07 Thank you for coming to the Pokémon Center! Please pick up your gift from the delivery girl in the game.  

Distribution Title Aaaah ! Un Ectoplasma chromatique ! Wondercard ID 524     PID Shiny PID Games XY Type Serial Code Dates Oct 9 2014 -
Feb 5 2015 Species Gengar Nickname (default) Gender Male Level 25 Nature Random Ability Levitate (1) OT OCT2014 TID 10134 Location a lovely place Ribbon Classic , Ball Dusk Ball Held Item Gengarite Moves Shadow Ball Sludge Wave Confuse Ray Astonish Relearn
Moves Sludge Wave Astonish (None) (None) Receiving Text 0x2C Thank you for coming to the store! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Diancie, le Pokémon fabuleux ! Wondercard ID 525     PID Cannot Be Shiny Games XY Type Serial Code Dates Oct 23 2014 -
Feb 25 2015 Species Diancie Nickname (default) Gender Genderless Level 50 Nature Random Ability Clear Body (1) OT NOV2014 TID 11064 Location a lovely place Ribbon Wishing , Ball Cherish Ball Held Item Normal Gem Moves Diamond Storm Moonblast Reflect Return Relearn
Moves (None) (None) (None) (None) Receiving Text 0x2C Thank you for coming to the store! Please pick up your gift from the delivery girl in any Pokémon Center. Distribution Text L'Orage Adamantin de Diancie en fait
un allié puissant ! Tranférez-le
dans Pokémon Rubis Oméga ou dans
Pokémon Saphir Alpha pour le faire
méga-évoluer quand vous aurez
sa Méga-Gemme !  

Distribution Title Un Dracaufeu Chromatique ! Wondercard ID 537     PID Shiny PID Games XYORAS Type Serial Code Dates Mar 21 -
Jul 19, 2015 Species Charizard Nickname (default) Gender Male Level 36 Nature Random Ability Blaze (1) OT PRINT. 2015 TID 4015 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Charizardite Y Moves Overheat Solar Beam Focus Blast Hold Hands Relearn
Moves Hold Hands (None) (None) (None) Receiving Text 0x35 Thank you for receiving this distribution! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Un Dracolosse prêt pour le combat ! Wondercard ID 538     PID Cannot Be Shiny Games ORAS Type Serial Code Dates Jun 22 -
Oct 12, 2015 Species Dragonite Nickname (default) Gender Male Level 55 Nature Random Ability Multiscale (HA) OT JUN2015 TID 6225 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Lum Berry Moves Dragon Dance Outrage Hurricane Extreme Speed Relearn
Moves Extreme Speed (None) (None) (None) Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Diancie, le Pokémon fabuleux ! Wondercard ID 546     PID Cannot Be Shiny Games ORAS Type Online Wi-Fi Dates Jul 24 - 27,
2015 Species Diancie Nickname (default) Gender Genderless Level 50 Nature Random Ability Clear Body (1) OT Hope TID 7245 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item None Moves Diamond Storm Moonblast Dazzling Gleam Protect Relearn
Moves (None) (None) (None) (None) Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center.  

Distribution Title Un Rayquaza chromatique ! Wondercard ID 547     PID Shiny PID Games ORAS Type Serial Code Dates Aug 10 -
Nov 30, 2015 Species Rayquaza Nickname (default) Gender Random Level 70 Nature Random Ability Air Lock (1) OT Galilée TID 8055 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Dragon Fang Moves Dragon Ascent Dragon Claw Extreme Speed Dragon Dance Relearn
Moves (None) (None) (None) (None) Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center. Distribution Text Envolez-vous au combat avec un
Rayquaza chromatique surpuissant !
En plus d’être rare, il connaît la
capacité Draco Ascension, qui lui permet
de méga-évoluer. Rien ne l’arrêtera !  

Distribution Title Un Ténéfix ! Wondercard ID 551     PID Cannot Be Shiny Games AS Type Serial Code Dates Aug 5 -
Oct 31, 2015 Species Sableye Nickname (default) Gender Random Level 50 Nature Relaxed Ability Prankster (HA) OT Shigeshige TID 8055 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Sablenite Moves Calm Mind Will-O-Wisp Recover Shadow Ball Relearn
Moves Calm Mind Will-O-Wisp Recover Shadow Ball Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center. Distribution Text Ce Ténéfix fait partie de l'équipe 2015
de Shigeki Morimoto, designer en chef
des combats ! Admirez toute la puissance
de sa Méga-Évolution !  

Distribution Title Un Ténéfix ! Wondercard ID 551     PID Cannot Be Shiny Games AS Type Serial Code Dates Aug 5 -
Oct 31, 2015 Species Sableye Nickname (default) Gender Random Level 50 Nature Relaxed Ability Prankster (HA) OT Shigeshige TID 8055 Location a lovely place Ribbon Classic , Ball Cherish Ball Held Item Sablenite Moves Calm Mind Will-O-Wisp Recover Shadow Ball Relearn
Moves Calm Mind Will-O-Wisp Recover Shadow Ball Receiving Text 0x2B Thank you for playing Pokémon! Please pick up your gift from the delivery girl in any Pokémon Center. Distribution Text Ce Ténéfix fait partie de l'équipe 2015
de Shigeki Morimoto, designer en chef
des combats ! Admirez toute la puissance
de sa Méga-Évolution !