Game:

Pokémon Yellow (1998)

Duration: 0:35

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30

Hi ^^, enjoy another silly video because why not! :D If you like, check out the other three today. :]
Thanks MercenaryCorruptionVT for the thumbnail!

In a nutshell, drawing the party Pokémon menu sprites assumes that 0xFF (end of list) is not at the top of the menu; otherwise the game will update the menu sprites based on your Pokémon and in a specific layout, as expected.
However, there is a quirk if you place 'M (FF)/Q (FF) at the top (this also applies to the Japanese versions, where the earliest known way to access such a party is with the empty party glitch; where you try to use your Potion from the PC without ever getting a Pokémon).

Typically, you may not notice any garbage OAM sprites, but performing a number of actions directly before viewing the party will corrupt it or sometimes 'fix' a corruption (even if all of the OAM sprites are off screen); such as (unexhaustive list)
1. Viewing the Trainer Card (badges influence the OAM sprites).
2. Viewing the Hall of Fame (Pokémon influence it).
3. Accessing an elevator list.
4. Having the S.S. Anne set sail (actual visual event, not NPC message).

(Really anything that touches CC5B but it's possible some of these may be overwritten at an intermediate stage)

00:cc5b wBoostExpByExpAll
00:cc5b wHallOfFame
00:cc5b wFilteredBagItems
00:cc5b wNPCMovementDirections
00:cc5b wDexRatingNumMonsSeen
00:cc5b wVermilionDockTileMapBuffer
00:cc5b wMonPartySpritesSavedOAM
00:cc5b wUnusedCC5B
00:cc5b wTrainerCardBlkPacket
00:cc5b wPikaPicUsedGFXCount
00:cc5b wElevatorWarpMaps
00:cc5b wSlotMachineSevenAndBarModeChance
00:cc5b wAnimationType
00:cc5b wOaksAideRewardItemName

I tried looking for the most powerful, and a relatively viable way is by viewing a page of the Hall of Fame. I edited my save file for specific Hall of Fame data.

A599 (corresponding to certain Pokémon in the Hall of Fame)

ffffff

(The first OAM entry second-fourth, but the first byte (y-coordinate) is written as 0xD2 for some reason (on hindsight maybe that was the contents of A598?), so we 'dummy-out' the rest of this entry with three FF).

A59C (corresponding to certain Pokémon in the Hall of Fame)

101087011018880110284C0110304D0118284E0118304F0112386801124069011A386A011A406B0118109C0118189F01

(The OAM data displaying "Hi :]" and Clefairy, Pikachu at those exact coordinates on the screen).
Note that when you move the cursor, the game will still attempt to animate sprites (based on the Pokémon's remaining HP) by adding 0x40 to the sprite entry after few moments.

Other Statistics