How to Shiny hunt unintended Game Corner Mon with item underflow glitch (Glitch GC list manips)

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HOW TO SHINY HUNT UNINTENDED GAME CORNER POKEMON IN POKEMON RED/BLUE/YELLOW
INCOMPLETE GUIDE BUT WITH METHOD COMPLETE FOR TWO EXAMPLES
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Short guide [short?] (yeah I'm a stereotypical girl who talks too much ;_;) - (If you're familiar with item underflow glitch, or just want to see the raw
glitch, skip to Line 116)

(I'm sorry I don't know how to do RB RNG manips yet to confirm this is possible/haven't grinded it yet. Since Game Corner mon are from the same script, i.e
you can get by chance a Shiny Porygon without glitches from the Game Corner 9999 coins purchase despite it being a gift it should be possible.)

(Not mentioned:

1. alternative glitches for below 1(i+) which make it too complicated;
2. technical explanations (I'll make a longer version later which will be on YouTube in a description)
3. specific examples, e.g. "I want to grind for a Shiny Charmander this way. How can I get it?"
(at the moment is just one example item swap and NPC to talk to with a non-glitch Pokémon)

INTRODUCTION TO EXPANDED INVENTORY AND OBTAINING IT:


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1. Get expanded inventory
i. RB: old man (MissingNo.) glitch https://glitchcity.wiki/Old_man_glitch  Y: Fossil/Ghost MissingNo. with  https://glitchcity.wiki/Trainer_escape_glitch#Ditto_trick or https://www.youtube.com/watch?v=73fAlzIbi9k
ii. When you do the item duplication on slot 6 ensure
a) it's not a key item b) it's most efficient to use a consumable item except a Poké Ball, x1.
A good example is X Defense x1 in slot 6>encounter MissingNo. It will become x129. Now you have a choice.
iia) Either consume two of the item (it must not be a Poké Ball) in battle and catch MissingNo. or 'M or just do two battles where MissingNo./'M appear where you run or defeat it.
Before the second battle, toss two of the now glitched item slot 6 quantity which is x129. Toss two to get x127. Encounter either MissingNo./'M again to get a x255 stack.

;- Important note 1

MissingNo. is usually safe except for sprite and Hall of Fame corruptions in EN RB (note for FR, DE, IT, ES (IT/ES requires walk through walls
Safari Zone glitch to walk on shore) it's different; depending on your version a MissingNo. or 'M equivalent could freeze your game before battle,
and that's the sort of freeze that's potentially dangerous to save although may be rare; the information is scattered one source is
https://glitchcity.wiki/MissingNo.#Front_sprites ; those with 'fixes' originally potentially freeze, but if in doubt I recommend using an emulator,
using code 011F5ED0 on a non-English version except Japanese version and checking for a freeze).

;- Important note 2

Old man glitch is not possible in Japanese Red/Green/Blue/any Yellow including EN without arbitrary code execution/ROM hacking.
The Trainer escape/Mew glitch/Ditto glitch/Special stat encounter variants work in both EN Red/Blue and Yellow.
Due to details (e.g. different trade mon nicknames), the Trade NPC variant however can differ.


;- Important note 3

Glitch Pokémon sprites can differ heavily between languages.

;- Important note 4

If you do the catch method, don't send a level 0 MissingNo. or 'M (00) to a PC box/check if you have 6 Pokémon before catching a Level 0 one,
as withdrawing it may freeze/softlock the game. MissingNo./'M is not always Level 0. This actually depends on the player name. Though you don't have to, you can
make your player name the full length (AAAAAAA etc. ; be careful if you want to avoid Glitch Trainers; i.e. match name with Trainer https://glitchcity.wiki/The_Big_HEX_List ;
regardless of class they'll always use a (usually) glitch team; for more information
see https://bulbapedia.bulbagarden.net/wiki/Glitch_Trainer#Old%20man%20glitch%20method )


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(For further questions about these contact me on Twitter (@Torchickens) https://twitter.com/Torchickens )

;- Important note 5

Even though this sounds absurd, MissingNo./'M will corrupt your Hall of Fame upon viewing its front sprite (although at the moment I can't remember if
back sprite) in battle without saving the game. Although you usually save the game with saving, it's possible to save the game either by changing boxes, or
a corruption. This includes certain glitch Pokémon sprites including MissingNo./'M. This can be confirmed by playing the game in Stadium. When you encounter
MissingNo. it says "saving". Despite this, it only touches a bank with the Hall of Fame data. The main data is not affected and the save file is not too corrupt
to play; just the Hall of Fame is corrupted.

But if you don't want the involvement of any glitch Pokémon at all, you're still in luck (see note 6).

;- Important note 6

Options include (but not limited to)

i. (in a limited context only) SRAM glitch (that glitch sometimes called "beat Pokémon Yellow in 0:00"). It gives you 255 Pokémon, swap Pokémon 1 or 2 with 10
to get an expanded inventory of 255 total items, but you can release all your 255 glitchmon later, even though sometimes trying to deposit freezes,
but there are workarounds. https://glitchcity.wiki/SRAM_glitch

ii. Another one exclusive to Yellow is Pikachu off-screen glitch. You don't need any glitch Pokémon at all for this.
https://glitchcity.wiki/Pikachu_off-screen_glitch

You can either corrupt your inventory with it without arbitrary code execution in the 'runs invalid program counter' sense; or..

Set up arbitrary code execution with it, and just use it to get the expanded inventory if desired.

;- Important note 7

When you count bag or PC item positions, the very top item counts as item 1. Cancel also counts as an item for this purpose. The position is the actual number,
not the list position, so you have to count while doing scrolling. Note 'lag items' can slow you down and require tapping B . They can also be dangerous to the
save if you do scrolling with A, depending on the glitch item. You can actually go to https://glitchcity.wiki/Celadon_Mansion_safe_spot before handling the
expanded inventory, or in Celadon City itself, have a bush on the top-left corner of the screen (otherwise early from top left).

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2. Once you get a x255 stack, refer to https://glitchcity.wiki/Dry_underflow_glitch
;then https://glitchcity.wiki/Celadon_looping_map_trick
;then https://glitchcity.wiki/Expanded_bag_item_documentation_(Generation_I)

Now you have the expanded bag inventory required for this glitch. ^^

For more freedom, it's recommended to set up expanded PC inventory using the same method as well (deposit a x255 stack there).
This is because Game Corner Coins are stored there. Not only can you set it to 9999 if you permiss cheating, but also coin values over 9999; which certain
glitch entries of valid (or) glitch Pokémon may require for your Shiny hunt.
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'Finally the cheetahmen..'


1. Get an [item] x [quantity] (an example including a valid Pokémon normally unavailable from the Game Corner prizes is below). The item x quantity differs between the versions e.g. Red/Blue/Yellow/localizations of them.
2. Go to Game Corner prizes map
3. Swap the [item] x [quantity] with CascadeBadge (it may be always below a B2F x81 normally but atm need to do more research). It's item 40.
"That's Item 40 	wMapTextPtr 	D36C 	D36B 	The upper byte of the pointer to the text for the current map. " from https://glitchcity.wiki/Expanded_bag_item_documentation_(Generation_I)
- Note:  That probably needs changing to "The upper byte of the pointer '''table''' to the text for the current map."
however if not concerned with technical details ignore.

4. Talk to [specific NPC]; you're basically loading a glitch '''list'''; so e.g. "Charmander" and "MissingNo." and "Squirtle" etc. but not the ability
to change one Pokémon in a list at a time, with this exception:
i. Some results may vary based on other things you do/RAM e.g. say the Pokémon in the list is altered by the bag item ID or a bag quantity ID
but a more detailed explanation will be for a later draft.

Example 1 (EN Yellow):
Item = Rainbow Item x 81 [awkward because it's a key item, but you can get a x0 from Celadon looping map glitch (which is really x256) so deposit it
in PC 175 times
Specific NPC = Talk to the bald NPC

; Gives me the list -

4 4 Hy 17#3 coins
Missingno 4628 coins
8 pe #50 coins

Example 2 (EN Yellow):

Item = Marsh Badge x 81
Specific NPC = Talk to the black hair NPC

; Gives me the list -

Shellder #040 coins
Charmeleon ##7# coins
Doduo 200# coins

(Maybe you can get say Shiny Charizard by grinding/RNG manip for Shiny Charmeleon ^^)
(Do beware, some lists can cause "buffer overflows"; they can corrupt your party and name altogether and are dangerous)
Making your own possible items also requires technical knowledge. This is one of the reasons this is only an early draft.

See also https://pastebin.com/bbRJfFzz by Luckytyphlosion for "Pokémon Red" (I assume the EN version). This requires technical knowledge as well, but does list all possible 255 Game Corner lists (note if RAM list then it can be anything you desire, practically however that's more complicated). Both lists in Example 1 and Example 2 should be one of the
"GAME CORNER [X]", but as I did it with Yellow it's probably why I can't find a match in Lucky's Pastebin (that and he uses a different glitch Pokémon naming convention).

"(To be continued)" - Meowth voice

(But that's only good if you want a Shiny glitch Pokémon, which you can make tradeable to Generation II as an equivalent Pokémon)
(See https://glitchcity.wiki/Time_Capsule_exploit and https://glitchcity.wiki/Abnormal_Pok%C3%A9mon )
(This is another thing people have contacted me about having trouble with, so feel free to send me a message on Twitter. I'll try to walk through/check what
you may be doing wrong ^^)

Example 2 (EN Yellow)

; Important note 1

You still need the Coin Case lol ;) (sadly :[ ); so make sure it's in the expanded inventory before you get it, i.e. keep it below your x255 stacks, even though
you temporarily can't select it when it changes from 0 items to 255 items you can again.

; Important note 2

Mentioning again.

For more freedom, it's recommended to set up expanded PC inventory using the same method as well (deposit a x255 stack there).
This is because Game Corner Coins are stored there. Not only can you set it to 9999 if you permiss cheating, but also coin values over 9999; which certain
glitch entries of valid (or) glitch Pokémon may require for your Shiny hunt.

:- Quantity of PC item 53 is byte 1 (x153)
:- Quantity of item 54 is byte 2 (the glitch item called E#POKé#9 ## #'m4…… ##a  in Yellow or POKéTRAINER#: ###  in Red/Blue;
be careful not to press A on glitch items in general unless for a glitch specific to using them, as you could freeze and
potentially destroy the save, scroll past with B instead). This can be very fiddly without a safe zone (see the earlier
linked Celadon Mansion safe spot article) as you're at the PC without a known one except if you deliberately make a Glitch City
with one and can still access the PC.

-Shiny Pokémon should have the theoretical 1/8192 chance
-Written by Evie after request on how this is possible (handle YouTube/user/ChickasaurusGL or Twitter @Torchickens)
-Game Corner manip originally discovered by Pokémon Speedrunners for glitched categories e.g. luckytyphlosion