Tweaking
Tweaking is a glitch that first appeared in the fourth generation of Pokémon. It is caused by pressing the left and right buttons continuously whilst holding the up/down button and riding on a bicycle in fourth gear and going through a load line (a load line is from where the game loads the next area graphics). It saturates the DS's RAM making it impossible for the game to load the graphics and sometimes the values too. It is most easily done in Jubilife City. This glitch will throw up invisible walls or cause a section/route to become black, only seeing the shadows of trainers, items etc. In some cases, the player will be able to walk through a black wall. They may also be allowed to walk through signposts. Tweaking seems to have no negative consequences on the game's data. However, there is a slight chance that while tweaking, the game will freeze. This is solved by simply turning off the game and turning it back on.
According to some, tweaking may allow players to catch Arceus, Shaymin, and Darkrai; however, this is unconfirmed. If the player tweaks correctly, then a grassy area might appear. It is thought that the legendaries mentioned above can be captured there, however it could be just blank data that will cause the game to freeze, like using the walk-through-walls code on Red and Blue. It is not confirmed what lies within the grass, although some reports include finding a Bad Egg within the grass, after a three-second pause.
