Mew glitch: Difference between revisions

The Mew glitch works by exploiting a separate glitch called the Trainer-Fly glitch.  The Trainer-Fly glitch is caused by encountering a Trainer that can battle the player at any point in the Trainer's line of sight and escaping from them.  These Trainers are nicknamed "Long-Range Trainers" due to the long distance that they can spot the player being defined as the maximum allowed by the game and will spot the player the moment that they appear on screen in the Trainer's line of sight.  When the game draws any NPC on the screen, that NPC is first placed in their default direction (south) for one frame, before being updated to face their correct direction. For Long-Range Trainers, this causes their line of sight to point south for the first frame, before correcting to their intended direction. For that first frame, the player can still bring up the start menu and use any [[Field move]] or items from their bag.  If the player uses {{m|Fly}} or a similar move or item, then the player will be spotted by the Long-Range Trainer before the player flies away from them.  This causes the game to believe that the player is starting a battle when they are actually not, causing various values to be read improperly and creating the core of the glitch. Specifically, the map script of the route the player left is set to a value where the game is constantly trying to display pre-battle text and start a battle.

Afterwards, the player will regain full control and be able to access the menu at will.  Should the player return to the same location or floor as the Long-Range Trainer, the game will go to display the pre-battle text and start the battle. This pre-battle text is text using the textbox ID of the most recently seen textbox, which if doing a textbook Mew glitch is the start menu seen when the player goes to Fly to Lavender Town to go back to Route 8, resulting the Start menu popping up on its own; this is good, as the Start menu is always safe to have pop up this way. After closing the menu, the game will immediately start a battle due to the game being in a state where it is constantly attempting to display enemy trainer text and start a battle, and ends up generating a battle with a wild Pokémon based on the Special stat of the Pokémon last battled and at a level based on the attack stage modifier of the Pokémon last battled. Note that if the Special stat of the Pokémon last battled happened to be in between 200 and 255, the player will instead encounter an enemy trainer, as trainer IDs are stored on the same table as Pokémon IDs. This trainer will have a roster based on the attack stage modifier of the Pokémon last battled. Avoid fighting Pokémon with a Special stat of over 248 without a lookup table of trainer IDs to avoid fighting [[ZZAZZ glitch]] trainers, as they corrupt the game.

The first documented and most commonly known method to perform the Mew glitch involves the {{tc|PI|Gambler}} on {{rt|8|Kanto}}, who is facing north towards the {{OBP|Underground Path|Kanto Routes 7–8}} entrance, and the {{tc|Youngster}} on {{rt|25|Kanto}} who is facing north and has a {{p|Slowpoke}} on his team. The player must have defeated neither Trainer before, and must also have a Pokémon who can use {{m|Fly}} on their team.

The player must stand directly beneath the Underground Path entrance door, at which point the aforementioned Gambler will be exactly one tile offscreen. It is recommended that the player [[save]] the game at this point in case a mistake occurs in a future step. The player then can begin the glitch by taking one step down, and then pressing and holding the Start button while the step is occurring. The Gambler will be scrolled onto the screen during this process and the player will enter his line of sight, but the start [[menu]] should appear before the Gambler "sees" the player.

In {{game|Yellow}}, the player can first catch Mew prior to the '''Quick Mew glitch''', using the exclusive {{tc|Bug Catcher}} Long-Range Trainer in [[Viridian Forest]] and the {{tc|Super Nerd}} in {{DL|Mt. Moon|B2F_4|Mt. Moon B2F}}.

# Next, the player should clear their way through [[Pewter City]], {{rt|3|Kanto}}, {{rt|4|Kanto}}, and [[Mt. Moon]] stopping prior to the Super Nerd with the two fossils on B2F. While doing this, the player should skip one trainer on the way that can take at least one step to initiate battle.

# Once the Koffing has fainted and the battle has ended, the player, without moving, should use their Escape Rope to return Pewter City. If any Pokémon battle is triggered after Koffing, the glitch will result in a Pokémon other than Mew.

# Finally, the player should head south to Virdian Forest avoiding the grass on {{rt|2|Kanto}}. Once the player enters Viridian Forest, the start menu opens automatically. After the player closes the start menu, a wild Mew will attack.

It is not required to use the {{tc|Camper|Jr. Trainer}} or {{tc|PI|Gambler}} to escape from, and instead the player can use any long-range trainer to trigger the glitch, using any type of warping field move such as {{m|Dig}} or {{m|Teleport}}. In order for the player to obtain Mew they need to fight a Pokémon with a special stat of 21 (the easiest way is to fight the {{tc|Youngster}} on {{rt|25|Kanto}} or the {{tc|Swimmer}} in [[Cerulean Gym]], if the player hasn't previously fought either), then return to the route with the long-range trainer without fighting another Pokémon.

The easiest way to manipulate the last encountered Special stat when performing the glitch is to first obtain it on the player's own Pokémon, and battle a wild {{p|Ditto}}. Send out the Pokémon with the desired Special stat on itself, and wait for the wild Ditto to use {{m|Transform}}. As the move Transform copies all of the target's stats, the Ditto will take on the Special stat of the Pokémon sent out. After defeating it or running away, proceed as normal, being sure to not battle any other Pokémon before the end of the glitch. The player must be sure not to [[Caught Pokémon|catch]] it, because if the Ditto is captured, the result will be based off Ditto's Special instead.  

In {{game|Yellow}}, as wild Ditto can only be found in the basement of {{ka|Pokémon Mansion}} or [[Cerulean Cave]], it is highly recommended to bring an Escape Rope or a Pokémon that knows Dig, in order to leave the Mansion immediately after battling the Ditto. If the player attempts to walk out of the Mansion and encounters another wild Pokémon on the first floor, its Special stat will overwrite that of the Ditto and cause a different Pokémon than the one desired to be encountered.

As it is easily possible for one's Special stat to exceed 190, the highest index number of a valid Pokémon, the Ditto glitch allows easy access to several [[glitch Pokémon]] for Special stats of 191 or higher. For example, in Red/Blue, a Special stat of 198 will lead to battling a [[ゥL ゥM 4]]. If the Special stat is between 200 and 255, the player will instead battle a [[glitch Trainer]] instead of a wild Pokémon. It is even possible to battle [[Professor Oak]] in this way. The Special stats 248, 251, 252, 254 or 255 (and sometimes [[Jacred|200]] if Growl is used once or twice), plus 249, 250 and 253 in [[Pokémon Yellow]], correspond to invalid {{DL|Pokémon Trainer|Trainer classes}} and may lead to the memory-corrupting [[ZZAZZ glitch]] depending on the level/roster value (which defaults to 7; see [[:#Level and roster manipulation|level and roster manipulation]]). As the ZZAZZ glitch can be hazardous to the [[save]] file (specifically, overwriting a large portion of memory with hex 99, resulting a heavily corrupted file that most likely cannot be saved), performing the Ditto glitch with these Special stats should be avoided.

To perform the above particular Snorlax skip glitch (assuming the goal is to complete the game as fast as possible), the player must first enter Route 12 (from the {{rt|11|Kanto}} side), in order to load its removable objects list into memory including Snorlax. The player must then head through [[Vermilion City]] and perform the Trainer-Fly glitch from a long-range Trainer on either {{rt|6|Kanto}} or Route 11, escaping back to Vermilion City. The player can complete the Trainer-Fly glitch by battling any Trainer on Route 6 or 11 (whichever the long-range Trainer is not on) and returning to the other route to trigger the Special encounter. Upon battling whatever wild Pokémon was generated on Route 6, the game will attempt to delete a sprite from the removable objects list currently in memory. As Route 11, Vermilion City, and Route 6 are all free of removable objects, the list currently in memory will be that of Route 12, and the Snorlax will disappear after the battle ends.

This can be also one of the side-effects of the Mew glitch. If the player causes a text box to pop up before returning to the area where the long-range Trainer was escaped from, such as by talking to an NPC or reading a sign, then something other than the start menu will pop up at the end of the glitch, due to having a textbox ID other than 0 saved into memory. This is typically dialogue from Trainers on the route, which may be followed by a wild Pokémon battle, after which the player will no longer be able to move.{{fact}} Alternately, the text may be from interacting with a sign or an item; in the latter case, the item will appear in the player's inventory and disappear from the route as if they had picked it up normally. This may also allow the player to obtain items which are not currently on the route. Finally, instead of a visible text box, the player may trigger other glitches, such as [[glitch song]]s or [[0 ERROR]]. Glitch songs are caused by invalid glitch textboxes that contain text script sound commands, and 0 Error is caused by any text box whose text script initiates a trainer battle, as it overrides the battle spawned by the Mew glitch and increments the map script to an invalid state.

At this point, there are a number of methods that can be used to complete the glitch:

* As the above method is tedious, a much simpler alternate method is to simply go to [[Pewter City]] and talk to the NPC who brings the player to the Museum (the player must choose No to his question, so he will actually walk the player there). When he is done moving, the game is done waiting. However, the player must encounter a Pokémon after this to get an actual Special stat loaded into memory. The Start menu must also be flashed after this, to prevent a possible text box error (see above).

* As the Museum person is vulnerable to the Snorlax skip glitch side effect (see above), the above method may fail to work after being used once. An even simpler alternate method is to simply push any [[Strength]] boulder, which will count as an NPC moving, because apparently Strength boulders are really NPCs. (No other [[HM]]s behave this way as none of them move sprites or objects.)

Note that as long as the player has at least one undefeated Trainer in a different area than the long-range Trainer, they can avoid having to do any of the above indefinitely, as all that is needed is for an NPC to finish a movement script that disables player input for the duration of the script and for a Special stat to be loaded into memory. It is not necessary to defeat another Trainer after escaping, only battle one, so a player can deliberately lose to a Trainer and continue on with the glitch, and that Trainer will remain battleable. However, if the player loses to that Trainer and then goes back to the area of the long-range Trainer and battles a Pokémon with this glitch, the long-range Trainer will no longer be battleable.

Using the "dry" variation of the [[item underflow|item underflow glitch]], which does not require an event that takes an item from the player's item pack (it is not required to have a Fossil or have the Saffron guards be thirsty), it is possible for the player to obtain a stored PC item counter of 255.