Game freeze

A game freeze occurs when the data completely stops flowing to the system, thus causing the game to lock up. During a game freeze, the player cannot move, speak to other characters, select an object, or use any buttons. The only way to escape a game freeze is to simply turn the power off and restart the game from the player's last save file.

Causes
Game freezes can occur due to invalid or unrelated information being input into the game, such as when walking out of the boundaries of an area. They also occur when performing glitches such as the Mew glitch incorrectly. Older cartridges and systems are also more prone to freezing than newer ones. The most common cause of a game freeze is the game being given too many tasks at once. For instance, there is a higher probability of the game freezing when the player tries tweaking. Incorrect cheat codes used on cheating devices such as Action Replay or GameShark can result in game freezes. On rare occasions, incorrect cheats may possibly render the save file unplayable and permanently damaged.

The game may also freeze if it is dropped, hit by any major force, has a dirty game cartridge/card, has been physically removed from the slot, or even if it is played on a faulty system (such as a Game Boy Color with low battery level). Game freezes are not limited to handheld systems, and it is possible for some home consoles to freeze up during gameplay. Leaving out of bounds by using the walk through walls glitch/cheat also freezes the game. A Game Boy Advance Pokémon game may freeze if the GBA itself is shocked by static electricity.

Game freezes are often accompanied by an odd buzzing sound; however, sometimes the normal music for wherever the player was before the game froze can be heard. Frequently, a loop or constant replay of whatever sound was being played prior to the freeze will be played. Sometimes, a freeze will play no sound, even if there was a sound being played before the freeze. In very rare cases, the music (and not the remaining sounds) can be the only thing to freeze, leaving the game still playable. Sometimes game freezes are accompanied by garbled sprites, various vertical lines and other scrambled graphics pixels and/or tiles.

The game may occasionally freeze while playing some copies of when a player's Pokémon uses  or, or when fleeing from a wild Pokémon; however, cases of the glitch actually occurring are exceedingly rare. The problems caused by the glitch occurring can be rectified by turning off the battle effects. The moves only cause a temporary repeat of the sound, and it will go away if the Pokémon taking the damage is defeated.

"Softlocking"
Certain glitches do not cause the game to outright crash, but rather make it so that no buttons have any effect despite the game continuing to function in other ways. Examples of this include the music still being played, sprites still being animated, and NPCs continuing to move. All inputs fail to work and the player must reset the game.

In Generation I

 * In Generation I, a level 1 Pokémon or a level 171 using will cause the game to softlock. The level 1 soft lock occurs as the game attempts to generate a random number between 0 and 1.5 × the user's level (rounded down). No such number exists (floor 1×1.5 is still 1), preventing the game from continuing. Similarly, 1.5 × 171 = 256 (0x0100), but because the game only retains the least significant byte, it treats the product as 0.
 * Glitch experience groups with an equation that involves a division by 0 can cause a soft lock for a glitch Pokémon that uses it after:
 * Capturing it.
 * Leveling it up.
 * Viewing the first page of its summary if it is not level 100.
 * Withdrawing it from a box.
 * Winning a battle with it gaining experience.
 * Talking to the Pokémon Day Care man after the Pokémon was stored there.
 * Using the Mew glitch incorrectly (Not making the second trainer move)
 * Another division by 0 glitch is caused while battling another Pokémon. If the attacker's Attack or Special stat is higher than 255 and the defender's Defense or Special stat, respectively, is lower than 4, or if the defender's current Defense or Special stat is 512 or 513 and the defender has used Reflect or Light Screen. Also if its current Defense or Special stat is 514 or higher when or, respectively, is up, it will be treated as if it was much lower due to a roll-over glitch.
 * The Pokémon Yellow glitch Pokémon 4(h4? (hex:ED) uses the glitch hex:FF experience group with a division of 0 in its current experience equation so it is affected by the glitch.
 * The Pewter Gym skip glitch allows the player to bypass the person blocking the path out of Pewter City prior to defeating Brock and then talk to him from the right side, an action the developers did not anticipate. As the path the person walks is dependent on the side the player talks to him from, the game attempts to look up a path based on the player's coordinates. Specifically, the game looks in the memory and tries find the coordinates (y=16, x=36 or hex:10 24) at an address ending in 2, 6, A or E. It then executes a path based on a two byte pointer following the coordinates, but the game may seemingly never find the coordinates at an applicable address and soft lock.
 * The glitch Pokémon will softlock while being sent out by the player.

In Generation IV

 * Performing the tweaking glitch can sometimes trigger a softlock or a game freeze.
 * When accessing the Void through either tweaking or the Surf glitch, if executed improperly it is possible to become trapped and unable to escape.
 * This also occurs when reloading the map over areas with water if the player hasn't obtained Surf and/or Fly.

In Generation VI

 * When saving in the North and South Boulevards of Lumiose City, the game may become unresponsive when it is reloaded. Some textures will not load properly and it is impossible to move or use the even though the background music still plays normally.

"Bar freeze"
This is caused when a "rst 38" instruction is run in Generation I. Most of the RAM is corrupted during this freeze with all accessible memory bytes being replaced with a "00 39" pattern. This includes SRAM which can damage the save data if SRAM was enabled. If the game was in SRAM bank 0 the Hall of Fame data will be corrupted, replacing the Pokémon in the Hall of Fame with level 57 Glitch Pokémon. If the game was in SRAM bank 1 the Continue option will disappear from the main menu without a "The save data was destroyed!" message showing up. If the game was in SRAM bank 2 or 3 Pokémon in boxes 1-6 or 7-12 respectively in the Pokémon Storage System, excluding Pokémon in the currently selected box, will be deleted.

In Generation II, a similar freeze is caused when a "rst 38" instruction is run. Bars will appear for a split second and then disappear. Like in Generation I most of the RAM is corrupted during this freeze, including SRAM, but SRAM is not damaged in Pokémon Crystal Version. If the game was in SRAM bank 1 the game will show "The save file is corrupted" error message when attempting to continue. If the game was in SRAM bank 2 or 3 boxes 1-7 or 8-14 respectively of the Pokémon Storage System will be corrupted and the only Pokémon in each of these boxes will be a level 57 Primeape Glitch Pokémon.