i am a speedrunner interested in utilizing the effects of the mail glitch in japanese sapphire as described here.
a particular application i am interested in is its ability to skip surf. i found that if you use the glitch to walk on water, then corrupt a tile into the secret base entrance (using a phrase such as "golduck", like in this video), then enter and exit the door, you will enter a surfing state regardless of whether you have a pokemon with surf, or even the balance badge, or even hm03. this could be accomplished on route 118 to skip most of western hoenn, in theory.
the problem is that the tile corruption always affects the same 9 tiles on a given map, making such an exploit impossible on maps where the location of the corrupted tiles does not permit walk-on-water. the wiki link above provides a table of coordinates of the corrupted tiles, but these coordinates appear to only apply to the mossdeep city map--other maps have their own coordinates. i am curious how the game decides which tiles to corrupt when using the mail glitch, perhaps a bit more of what the mail glitch is/does, and perhaps how we could exercise more control over which tiles become corrupted.
Hi g_heinz. Yes, this is a question I'm afraid I've never found the answer to. Certain maps do not work for the glitch, or the start of the affected tiles may be at different coordinates (e.g. Mossdeep City seems to be x=06, y=0C for keyword 1, but Sootopolis City is x=0B, y=11 and some maps do not have visible changes). These may be defined in the ROM or memory somewhere, but I haven't been able to find them after a brief look.
I did some extra research and this is what I found.
You can walk through some tiles in ways that would otherwise be unpassable (e.g. walking up, left, right through the "キングドラ" ledge), but there are other tiles which you cannot pass through.
In at least Route 113, where the corruptible tiles begin six-fourteen tiles west of Route 111, these include phrases including, most likely not limited to, あいさつ〉ありがとう ("thank you") - it looks like part of what AdvanceMap calls a border block, and あいさつ〉イエス (possibly "yes"), which is surprising because it looks like a passable tile.
Gloom (クサイハナ) happens to give you a water tile. If you have HM03 and the Balance Badge, you still cannot Surf on it from the menu at least.
グラエナ (Mightyena) will give you a ledge that will allow you to jump right. ポチエナ (Poochyena) will give you a ledge that will allow you to jump left. へラクロス (Heracross) or サニーゴ (Corsola) or キングドラ (Kingdra) will give you a ledge that will allow you to jump down.
Secret Base cave entrances seem to work like the Secret Base tree entrances - you have to enter them from below to access the warp.
Memory address 02001014 controls the middle Mail phrase. These correspond with tile index numbers, and a tile index number can be looked up in AdvanceMap if you assume the top-left tile (black space) as ID 0000, the plain grass tile that follows as ID 0001, and so on.
There is a way to obtain a hex:0000 ????????. I'm unsure if this is useful in any way, and I wasn't able to sell it, but I got it after activating glitch 2 and immediately giving another Pokémon (other than the original) Mail and confirming the phrases without changing them. You can continue to give it Mail from the Pokémon menu and accessing the items with give (not the items menu directly) to obtain multiple hex:0000 ????????.
Hope this may come in handy.