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Generation I Glitch Discussion

Hall of Fame Corruption but worse - Page 1

Hall of Fame Corruption but worse

Posted by: CytricAcid
Date: 2020-05-03 17:52:23
Hi all! This is a somewhat continuation of my previous thread of Hall of Fame corruption. My intention back then was to document all the effects of glitch pokemon that appear in the HoF. During this, I discovered something important - any glitch pokemon that wasn't a hybrid of a "valid" pokemon species would have their sprite blanked out by the Rhydon Trap. This means, for most glitch pokemon, especially ones that can freeze the game, will not have such effects or appear in the HoF, leaving any kind of corruption in the HoF limited to the handful of glitch pokemon with valid families and improper sprites.

In fact, in Red and Blue, all the hybrid glitch pokemon in the game do not have freezing front sprites with dimensions of 0x0 (thats the only dimension that can do more than just corrupt the HoF that I'm aware of). However, in Yellow, there are two pokemon that are in fact hybrids and have front sprite dimensions of 0x0, which are 0xEC and 0xF4. If these pokemon appeared in the Hall of Fame or viewed in the status screen, they would likely have similar effects to Yellow Missingno.

And in fact, Evie already did a video about this in 2016, demonstrating that viewing their status screens will in fact cause overworld corruption though no lasting damage is done. I assume the same would happen if they were displayed in the HoF. So, I already have my answer. But I want to do more!
To get one of those pokemon and view their status involves catching them, and since you can't catch them because of their front sprites, you need to go through a really convoluted process using other glitches in order to catch it, as demonstrated in her video. That's all fine and dandy, but if you could just have it appear in the HoF, you could get all the benefits of corruption *right in your PC!*

So here's my plan - find a way to make one of those pokemon appear in your HoF, through the back and/or front sprites of other glitch pokemon.

We can already do the corruption through catching the pokemon in a convoluted manner and viewing it's status, but I want something thats easier to set up. Trainer Fly is a pretty simple glitch to perform, but we're limited to pokemon that have IDs less than 200 or any glitch pokemon that do appear on the teams of Trainer Fly pokemon trainers. We can also use pokemon that appear in the HoF to corrupt it further, like a terrible recursive loop of corruption.

How easy this is depends heavily on how deterministic HoF corruption is. Are the corruptions constant or not? What are the patterns? Is it safe to just encounter 1 glitch pokemon enough times until it corrupts one of the pokemon to be 0xEC or 0xF4, or do only specific pokemon appear in the HoF based on the front sprite encountered? How can we manipulate it so that one of those two bytes appears in HoF data? I think this could be really interesting to look into. We already recently got a video going over how pokemon sprites are decompressed recently, but I don't recall the corruptions being constant. Is it possible to just continually encounter pokemon with a glitch pokemon's huge backsprite and eventually corrupt the HoF in just the right way, or is this result only possible with certain glitch pokemon's front and back sprites?

There really is no purpose to this other than for fun, and possibly explore the effects of those glitch pokemon's sprites without having to use glitch items or ACE. Yellow Missingno, obviously, has similar effects, but I think the possibility of accidentally triggering it through corrupted Hall Of Fame data is really funny and unexpected.

Re: Hall of Fame Corruption but worse

Posted by: CasualPokePlayer
Date: 2020-05-03 23:28:39

Are the corruptions constant or not?

Yes, assuming HoF starts with the same values (rst 38 it lol). The corruptions are effectively an LFSR https://en.wikipedia.org/wiki/Linear-feedback_shift_register

What are the patterns?

You bruteforce it :P

Is it safe to just encounter 1 glitch pokemon enough times until it corrupts one of the pokemon to be 0xEC or 0xF4, or do only specific pokemon appear in the HoF based on the front sprite encountered?

Why encounter when you can just view the summary. Enough times you should be able to find pretty much anything.

How can we manipulate it so that one of those two bytes appears in HoF data?

You bruteforce it until it pops those 2 bytes in front of the HoF.

Is it possible to just continually encounter pokemon with a glitch pokemon's huge backsprite and eventually corrupt the HoF in just the right way

Yes

Is it possible to just continually encounter pokemon with a glitch pokemon's huge backsprite and eventually corrupt the HoF in just the right way


or is this result only possible with certain glitch pokemon's front and back sprites?

Maybe if you want to manipulate a string of bytes, maybe, but mostly no.


Also something like this was already done by zzazz way back :P
https://www.youtube.com/watch?v=_-wVsN8rVks

Re: Hall of Fame Corruption but worse

Posted by: Torchickens
Date: 2020-06-21 13:54:00
Yeah :( getting 0xEC and 0xF4 without GameShark is trickier/needs more precise requirements, but you can get it with arbitrary code execution (see this post and TheZZAZZGlitch's reply where you can use quantities 236 and 244) or Rival LOL glitch if not afraid to use them. Other options are possibly specifically made non-Rival name CoolTrainers/LGs and the remaining HP glitch, international Fossil Conversion glitch, connection copier, possibly bad PC boxes [all except the last and specific non-Rival 0xEC/0xF4 CT/LG are on the wiki. On that note luckytyphlosion shared CoolTrainer logs which I mirrored here https://sites.google.com/site/torchickens2/glitch-city-laboratories-resources ; but for Red/Blue and I'm unsure if he ever did any for Yellow. I can teach how to use the Red/Blue ones, though.]. Note for the ones that display the Pokédex entry it's good to register Pidgeotto in advance, in case the Pokédex entry freezes the game (which just happened to me while testing).

I'm unsure of a step by step method from sprite corruption sorry, but you can also enter the Hall of Fame for the first time and register 0xEC and 0xF4 there. ^^ The corruption essentially only occurs if Hall of Fame data [as in accessible from the PC, not just corruption before you can access it I don't think] already exists (maybe technically it does corrupt but maybe the new entry re-initialises it with the Pokémon you actually had in the party, regardless if they're glitch Pokémon or not) . With the expanded inventory you can change D364 (item 36 quantity) to x118 to warp directly to the Hall of Fame room if you prefer, to register there without battling the Elite Four and Champion.

Unfortunately on the induction 0xEC as the first entry just played the Game Corner music, while 0xF4 made some corruption to the music (not changing the current track or playing a partial song but corrupting music channels) and played a cry, but not enough for any visible changes (unlike with the party status). With 0xEC as the second entry that may have made some music corruption like 0xEC as the first entry too. Viewing the Hall of Fame from the PC option didn't result in visible corruption either (I think I tried it with them as both entry 1 and 2 too, but still there was no visible corruption).

So from what I tried it does less corruption this way and it might not be possible to get unique visual effects/only music/Hall of Fame corruption, sorry. :(

Re: Hall of Fame Corruption but worse

Posted by: Torchickens
Date: 2020-07-17 11:18:04
For what it's worth, I made some Game Genie codes to change the first four Pokémon in the credits sequence; in order first to fourth; XX0-28A-800 XX0-29A-5DE XX0-2AA-A22 and XX0-2BA-6E6. I tried a few glitch Pokémon like 4 4, and MissingNo. Unfortunately like on the summary screen they showed no picture and no glitches were seen. However, 0xEC and 0xF4 are also exceptions. You can force them in the credits but it seems they just corrupt the music? I haven't checked my Hall of Fame, though.

[img]https://i.imgur.com/V66YKMj.png[/img]