Part 57: Side Notes #12: The Mew Glitch And How The Hell It WorksSide Notes #12: The Mew Glitch And How The Hell It Works
So I did some pretty crazy shit in the middle of this update. What the hell did I do? Let's break it down.
The reason the glitch works is because you escape from a trainer's sight, confusing the game into believing you're in a battle, causing various values to be read improperly. This means you can't open your menu, so the second encounter of the glitch must be easily accessible as well as have the right Special value.
The Special stat of the Pokemon battled last is important, since it matches up with the index number of the wild Pokemon you will later encounter. Mew's Index Number is 21 and the Slowpoke has that Special value. If you used the version that gets you Mew before Misty, then the Swimmer's Shellder in the Gym also has a Special of 21. The one used is the last one encountered, so fighting another trainer or Pokemon will result in a different Pokemon then expected.
This glitch allows you to encounter every single Pokemon in the game, so long as the Special value matches up. So, if we did 20 instead, we would encounter Arcanine. 22 would be Gyarados. Pokemon account for 190 of the index numbers, but those that aren't an actual Pokemon are, of course, Missingno. Though we cannot do the item duplication trick in Yellow, we can still encounter a large variety of Missingno., with quite a few of them different to the ones in RGB. I'm not experienced in that way, so I won't be showing all that crazy shit.
Even more interesting, a Special between 200 and 255 allows you to encounter trainers of every class. We may use that in future, but you need to be careful of a couple of things. If you go any higher than 255, it loops back around, allowing you to more easily encounter the Pokemon at the start of the list, like Rhydon, using a Special of 257, as 256 equates to 0 and does nothing.
But how would you be so precise? Well, the cheat works on any wild Pokemon as well, but they could have a range of Special values depending on DVs. While it could be fun to see what crazy shit you get, if you want a specific value, then the easiest way is to have your own Pokemon have that value and get a Ditto to Transform into that Pokemon. But it has to be the last Pokemon encountered, so using an Escape Rope or Dig to ensure you encounter nothing else is the best way.
So another thing, why was Mew at level 7? That matches up exactly with the Attack stage modifier, where -6 is level 1, +0 is level 7 and +6 is level 13. So if you have a way to manipulate that, then you can get some Pokemon at very interesting levels, including level 1, which is another load of glitches we won't be getting into, more commonly seen with the Missingno. item stuff. There's no move to increase the enemy's Attack, but you can lower it, or have the transformed Ditto increase its own Attack with a move it copied. This is used to battle a specific trainer's roster, more often than not.
Every trainer has a roster they use in the game. For a lot of Gym Leaders and the like, they have 1 roster, so to easily encounter it, you reduce the Pokemon to -6 attack. But if you don't reduce it that much, then the game doesn't break, it just moves in a line, so if the Pokemon had -5 Attack, but the Special value matched to Brock, then instead of encountering Brock's 2nd roster, you encounter Misty's 1st roster. There are some trainers which have more than 1, so you lower or increase the Attack depending on what you want. There's a lot of freedom involved.
There are actually a lot more applications for this glitch then just the ones listed, including how to have it happen if you have no trainers left, or by whiting to a wild Pokemon on the same square a trainer would see you, or using the PC to get your buttons back so you can challenge the Elite Four, but you can find those on your own.
One very interesting application is to have the glitch occur on or near a route that has a stationary encounter, so long as it's in memory. By doing this, the game just assumes that you are doing that particular encounter (such as the Snorlax on Route 12) and once it ends, it'll delete that sprite, since as far as the game knows, you didn't have a random encounter, so you must have faced that Snorlax. However, if you do this and there are no stationary encounters where the game expects it to be, then it may delete other sprites that can be removed, such as item balls. That's why Route 8 is preferred, since there are no deletable objects to begin with, so you can perform the glitch there as many times as you like.
It's a shame I won't be showing too many glitches this game has to offer, since some are a bit difficult to pull off, or they'll disrupt the gameplay in some way, or I just don't know how to do them. In any case, this is another reason why Gen 1 is so fascinating to me.