Question marks

Question marks are often used to indicate things in the Pokémon games that are unknown:

In the core series

• The ??? type, a type used in Generation II, III, and IV.
• A form of Unown.
• The Pokédex number of an obtained Pokémon not in a regional Pokédex in Generation IV, V, and VI.
• The ID number, OT name, and National Pokédex number of a Pokémon Egg.
• The placeholder name of Silver in Pokémon Gold, Silver, and Crystal, before he is given a name by the player.
• The location of the player while inside of a truck at the beginning of Pokémon Omega Ruby and Alpha Sapphire.
• In Pokémon Sun, Moon, Ultra Sun, and Ultra Moon, Ultra Beasts that have not been owned display ??? in place of their name. Nihilego is displayed as ??? when battling it in Aether Paradise.
• In Pokémon Sword and Shield at the start of the game, the player finds a Pokémon, later revealed to be Zacian^Sw/Zamazenta^Sh, labeled as ???.
• In Pokémon Sword and Shield's Expansion Pass, The Crown Tundra, Calyrex and, depending on which carrot they choose to grow, Glastrier or Spectrier, are fought as ??? when fought separately.

Glitches

• ?, a glitch type in Generation I and the main type of PPkMnp' '.
• ?????, a glitch Pokémon appearing in Generation II.
• ??????????, another glitch Pokémon appearing in Generation III.
• ????????, the item often held by ??????????.
• ? (glitch Pokémon), a glitch Pokémon that was used as filler for old Unown data in Generation III.
• ?????, a dummied out item in Generation I located at hexadecimal identifier 07, fan-named "surfboard".
• ?????, a dummied out item in Generation I located at hexadecimal identifier 2C that does nothing.
• ?, a dummied out item in Generation II located at hexadecimal identifier 00 that, when held by a Pokémon, the holder behaves as if it did not have the item.
• The description of several glitch items, such as Teru-sama.
• MissingNo.'s classification in the Pokédex.

In the side games

• In Pokémon GO, wild Pokémon with a Combat Power higher than the CP of the player's highest CP Pokémon have their CP displayed as ??? on the encounter screen.
• ?????? Coin, the original name of the Gimmighoul Coin in Pokémon GO.
• Meltan's name was ??? after Chikorita Community Day (before it was revealed to be called Meltan) in Pokémon GO

In the spin-off games

• In Pokémon Mystery Dungeon: Explorers of Time, Darkness, and Sky, missions with an unknown reward have the reward listed as ???.