Glitch fish: Difference between revisions

However, glitch fish slots using the Rod in maps that normally return "Looks like there's nothing here." are possible another way (using Game Genie) if the message is circumvented (i.e. if the length of the Super Rod encounter slot data structure is extended (it is usually terminated with 0xFF) or an invalid fishing group is accessed). There are artificial glitch encounter slots beyond the last slot (for Red/Blue these are the groups beyond group 10 (Fuschia City), for Yellow the structure is slightly different and glitch fish would relate to the slots beyond 31: Cerulean Cave B1F). As Rod encounters work by writing to W_CUROPPONENT (D059 in Red/Blue and D058 in Yellow), fishing for Trainers/[[glitch Trainer]]s is also theoretically possible.

The player can also simply lock W_CUROPPONENT or wEnemyMonSpecies2 (CFD8 in Red/Blue and CFD7 in Yellow) to any Pokémon or Trainer they want before the battle, however this method can be used to change which Pokémon appears in any case and is not specific to a glitch slot of possible fishhooked Pokémon.

{{GSC}} changed the way Rods originally worked in {{RBY}}. Old Rod and Good Rod encounters now vary based on the current map as well, in addition to the Super Rod; and even the Old Rod (still typically bringing up Magikarp) may fail with the message that there is not even a nibble. Furthermore, due to different coding/data structures, it is also possible to bring up glitch hooked Pokémon encounters (including both Pokémon and glitch Pokémon such as [[?????]]) when fishing from invalid maps using Rods (as there own glitch locations rather than Glitch Cities of valid maps) without having to use a Game Genie to temporarily patch the ROM. The hooked Pokémon (being invalid) can exceed Level 100, do not naturally have to be Pokémon that appear in the water, and in the case of ????? can have a status condition after the battle starts. Maps in Gold/Silver/Crystal each have a fish group, but fish groups beyond the last valid index number will result in invalid hooked Pokémon.

The player technically doesn't have to warp to or otherwise visit a glitch map to access the glitch fish specific to that map (altering wMapGroup DA00 and wMapNumber DA01 such as with a method of [[arbitrary code execution]] like the [[Coin Case glitch]] to partially change the current map without loading the rest of its data is enough. In Crystal, the equivalent addresses are DCB5 and DCB6. This method can be ideal for avoiding a [[game freeze]], as many (most?) glitch maps in Gold/Silver/Crystal will typically freeze the game when visited using a door.