SkyLink98

This event was announced during the Crown Tundra premiere in September 29th, 2020. Starting from October 9th, this Pikachu can be redeemed with the code V0LTTACKLEP1KA. This is the fourth Hat Pikachu available through Mystery Gift on Sword and Shield.

   Wonder Card ID #1629: Pikachu (Sinnoh Cap) Gift  Species   Pikachu (Sinnoh Cap)   TID   201023   Distribution   Serial Code   Location   a Pokémon TV program   Dates   Oct 09 to Nov 30, 2020   PID   Cannot Be Shiny   Games   SWSH   Nature   Hardy   Ability   Static (1)   Item   None    IVs   EVs HP ALL
RND   ALL
0 ATK DEF S.ATK S.DEF SPE
  Lv. 25       Moves   (ITALIC means Relearnable)   Thunderbolt   Quick Attack   Iron Tail   Electroweb   Extra Relearnable:   Volt Tackle

Classic Ribbon  Lang
 Slot    Mon's
 Lang    Nickname    OT Name   OT's 
Lang   JPN      (default name)    サトシ    JPN  ENG      (default name)    Ash    ENG  FRE      (default name)    Sacha    FRE  ITA      (default name)    Ash    ITA  GER      (default name)    Ash    GER  SPA      (default name)    Ash    SPA  KOR      (default name)    지우    KOR  CHS      (default name)    小智    CHS  CHT      (default name)    小智    CHT Only One Redemption Allowed  Format Ver.2.0.0-11b, Post Updated Date:20201101_2110

This event was announced during the Crown Tundra premiere in September 29th, 2020. Starting from October 2nd, this Pikachu can be redeemed with the code P1KAADVANCE. This is the third Hat Pikachu available through Mystery Gift on Sword and Shield.

   Wonder Card ID #1628: Pikachu (Hoenn Cap) Gift  Species   Pikachu (Hoenn Cap)   TID   201023   Distribution   Serial Code   Location   a Pokémon TV program   Dates   Oct 02 to Nov 30, 2020   PID   Cannot Be Shiny   Games   SWSH   Nature   Hardy   Ability   Static (1)   Item   None    IVs   EVs HP ALL
RND   ALL
0 ATK DEF S.ATK S.DEF SPE
  Lv. 25       Moves   (ITALIC means Relearnable)   Thunderbolt   Quick Attack   Iron Tail   Electroweb   Extra Relearnable:   Volt Tackle

Classic Ribbon  Lang
 Slot    Mon's
 Lang    Nickname    OT Name   OT's 
Lang   JPN      (default name)    サトシ    JPN  ENG      (default name)    Ash    ENG  FRE      (default name)    Sacha    FRE  ITA      (default name)    Ash    ITA  GER      (default name)    Ash    GER  SPA      (default name)    Ash    SPA  KOR      (default name)    지우    KOR  CHS      (default name)    小智    CHS  CHT      (default name)    小智    CHT Only One Redemption Allowed  Format Ver.2.0.0-11b, Post Updated Date:20201101_2109

This gift is distributed to players via a serial code, given in participating stores in Europe, from 25 September to 25 October 2020.
The codes are redeemable until January 31st, 2021 (Thanks @AlamosIT for the report).
Using the Dynamax Crystal would allow the Pokémon to appear at the Watchtower Lair's Den as a max raid.
The Pokémon can be Shiny with standard odds. Attached there are the wonder card, the standard Pokémon and the Shiny variation.
To be able to use the items associated with the event, including injecting items into the save and getting it to work,
the player's Switch must be connected to the internet, with the Mystery Gift>Get Wild Area News option used during the event period.
Alternatively the player must have connected to the internet and redeemed a Mystery Gift during the event period.
This gift can be redeemed on either Sword or Shield.
This events also has a certain fixed IVs.
As of time of writing, end date for the serial code redemption is presently unknown.
In order for the item (whether redeemed or hacked in) to function, players would need to have at least Wild Area Event #24 downloaded into the save.
(When collecting a Mystery Gift, a copy of the Wild Area News would be downloaded to the save) As of LGPE, wonder cards are no longer stored in saves. As such, players will not be able to inject this event into their save using PKHeX.
  Wonder Card ID #0506: Dynamax Crystal Gift   Here's what you got:    ★Sgr6859 x1                                  Serial Code | SWSH | Only One Allowed | Sep 25, '20 to Jan 01, '21 Original news with more details:
 

This is a save file with a recreation of 426 Legal ROCKS METANG.
This event was distribuited to players during the Rocks America Tour in 2005. 
Pokémon Characteristics: 
TID 02005, SID 00000, OT Male ROCKS, National Ribbon
Moves: Take Down, Confusion, Metal Claw, Refresh
Origin Game Ruby, Fateful Encounter as Met Location, Caught in Pokéball, Met at Level 30
ENG, Lvl 30, Clear Body as Ability
PID and IVs matching the 10 ANNIV Distribution Method.

This save file is based on @GalosAlan10 and @Sabresite's Celebi Save File:

ROCKS Metang share the same generation algorithm as 10 ANIV and Aura Mew Events: