From Bulbapedia, the community-driven Pokémon encyclopedia.
This is a list of glitches that occur in the Generation VIII core series Pokémon games.
Sword and Shield
Baton Pass Own Tempo glitch
If a Pokémon with Own Tempo is confused due to obtaining it from Baton Pass, it will not be cured of confusion until after a Pokémon takes its turn (uses a move, switches out, etc.).
This glitch was also present in the core series Generation V, VI, and VII games.
Berry tree glitch
This glitch involves shaking a Berry tree from behind. It ultimately allows for the player to walk through walls.
When a Pokémon is Dynamaxed, if the player looks at the party screen, the moves will be listed as if the Pokémon weren't Dynamaxed (Example: Rock Slide, Rock Blast, Sandstorm, Stone Edge). However, when checking the summary screen, the moves are displayed as Max Moves, in this case, Max Rockfall (three) and Max Guard.
Evolution cancelling glitch
If the player cancels evolution of a Pokémon, the proper stamp will appear on the Y-Comm regardless.
Fairy Lock crash
In Pokémon Sword and Shield v1.1, if a Pokémon uses Fairy Lock while animations are enabled, the game crashes. Due to no Pokémon that can learn the move being present in Pokémon Sword and Shield at the time of this glitch's existence, the only way for this to legitimately occur is when the move is called via Metronome.
The crash does not occur if animations are disabled. This crash was not present in Pokémon Sword and Shield v1.0, and was fixed for v1.1.1.
Ingredients seller glitch
When the player cycles behind an ingredients seller he will turn around. He can then quickly go back round behind him and interact without him turning back again. When the player talks to him, his back will be turned to them.
Isle of Armor Pokédex glitch
If the player brings a Pokémon that was introduced as part of the Isle of Armor expansion from Pokémon HOME, the In-game Pokédex would not add it's entry. this was fixed when the Switch version of Pokémon HOME was updated to version 1.1.1
June-July 2020 Wild Area News event glitches
When the June 30, 2020-July 31, 2020 Wild Area News event began, it contained an error in which a nonexistent item was part of the item drops awarded for completing a Max Raid Battle tied to the event. The game attempting to reward the player with the nonexistent item caused a glitch that crashed the game after viewing the item drop list. This glitch was quickly fixed in two stages, first removing the nonexistent item from the item pool and then replacing it with the intended item, the Armorite Ore.
While the nonexistent item glitch was being fixed, another glitch occurred which prevented any Max Raid Battles associated with the event from being initiated while the game was connected to the Internet. This glitch was removed at the same time as the corrections to the nonexistent item glitch.
List item glitch
The glitch in effect (affects Nuggets
When the player finishes a Max Raid Battle induced by an event or Wild Area News, some list items will be shown separately.
At certain precise locations, entering a battle causes the game to believe the player is in the wrong area when the battle ends. This can be exploited to catch weather-dependent Pokémon, or obtain Pokémon with an impossible encounter location such as the Meetup Spot. 
Memory feeling off-by-one bug
The feeling displayed in a Pokémon's memory for Pokémon transferred from Generation VI are displayed incorrectly. Pokémon that display the feeling "it was happy" in Generation VI instead display an empty string (or the same as the last checked Pokémon's feeling if another Pokémon's memory has been checked), and all subsequent feelings are displayed as a different feeling, shifted by one with respect to their index number.
This is due to the fact that in the Generation VI games, feelings are indexed from 0, while in the Generation VIII games, feelings are indexed from 1. Since the internal value storing the feeling in a Pokémon's memory is neither modified when a Pokémon is transferred from Generation VI to Generation VIII through Pokémon Bank and Pokémon HOME nor specially handled in Pokémon Sword and Shield, the displayed feeling appears to have been changed despite the internal value remaining unchanged.
Memory place change bug
The places displayed in a Pokémon's memory for Pokémon transferred from Generation VI with memories that mention places introduced in Pokémon Omega Ruby and Alpha Sapphire (such as "a Secret Base", "a Contest Spectacular Hall", or "oh, while soaring in the sky") are displayed incorrectly. For example, a Terrakion with a memory of being caught at the Pathless Plain would display in Omega Ruby and Alpha Sapphire as being caught at "a tiny island", but this memory would display as being caught "in a Secret Base" once transferred.
This is due to the fact that these strings are listed in a different order internally compared to Omega Ruby and Alpha Sapphire. Since the internal value storing the place in a Pokémon's memory is neither modified when a Pokémon is transferred from Generation VI to Generation VIII through Pokémon Bank and Pokémon HOME nor specially handled in Pokémon Sword and Shield, the displayed place appears to have been changed despite the internal value remaining unchanged.
A glitch which allows the player to move the cursor in a frame just before using an Experience Candy or starting an evolution. This applies the item/evolution sequence to the other Pokémon, and allows for major consequences such as evolving underleveled Pokémon (if the first Pokémon is of the same species), male Salandit, Combee (which become female Salazzle, Vespiquen), special event Pokémon that normally cannot evolve but can be forced to via level up and this glitch (involving event Meowth, Eevee) and Pokémon inside Eggs. If the species do not match, or evolution is impossible, the game may halt on an error message; closing the software.
The glitch appears to have been patched in v1.2.1.
Move Reminder glitches
These glitches occur when attempting to use a Move Reminder when there are at least 67 available moves (e.g. this can be done with a Mew which previously knew many Technical Records). It can cause the game to halt on an error message, closing the software. Other times, the player is able to see a glitched move (sometimes with a blank name, other times "———"). This glitch was found by SciresM.
Night Daze oversight
When used, Night Daze damage will not be accounted for on the target's HP bar for the rest of the turn, unless the move has caused the target to faint or something else changes its HP.
Rose Tower glitch
This glitch occurs when the player flies to another location from the outside of Rose Tower before going inside the tower itself. The map shows the objective "Search for the bad League staff member hiding around Wyndon Monorail Terminal!" despite having already done so by this stage of the game. This area is no longer accessible and prevents the story from progressing as the player has no other means of going back to Rose Tower. This glitch was found by hikaribruh.
Rotom Bike turning radius glitch
When the player uses the Rotom Bike's turbo boost, its turning radius becomes larger. If the player speaks to an NPC, a Pokémon egg hatches or picks an item on the ground during a turbo boost, the bike will continue to have a larger turning radius despite the boost stopping. The radius will reset if the player uses a second turbo boost.
Silvally Move Tutor glitch
Silvally is programmed to be able to learn all 3 Pledge moves; however, the Move Tutor offers only Grass Pledge, not Fire Pledge or Water Pledge.
This glitch was also present in the core series Generation VII games.
Sucker Punch/Quash glitch
In a Double Battle where the player who didn't initiate the challenge is down to their final Pokémon, that Pokémon's Sucker Punch or Quash will fail when used against the opponent on their right. This applies regardless of what move the Pokémon selected for the turn.
With the release of the version 1.1 update to Sword and Shield, this glitch was fixed and Sucker Punch and Quash can now correctly hit Pokémon in that position.
If an item can be consumed during switch-in, Symbiosis will activate it twice and consume the item that it passes.
Toxic sure-hit glitch
- Main article: Toxic sure-hit glitch
If a Poison-type Pokémon uses Toxic, any subsequent moves that Pokémon uses in the same turn (possible by using Toxic via Instruct or Magic Bounce) will always hit including when the target is in a semi-invulnerable state. This glitch also exists in Generation VI and VII. This was fixed with the release of version 1.3.1.
Trade Completed notification glitch
After a surprise trade has been concluded, if the Y-Comm is opened fast enough and the player starts another Surprise trade, the trade completed notification will still show (although the next trade completion will make it stop).
Trick Room oversight
If a Pokémon has an effective speed greater than 1809, it will ignore the effects of Trick Room, and act before slower Pokémon. This glitch also exists in Generation V, VI and VII.