The dark red selector glitch allows the player to change the color of the selector in the START menu. This glitch is not present in Japanese versions, because they use an arrow as a selector, rather than a red box.
RequirementsThis glitch is currently known to work in these locations: The Berry Master's house, while raining Petalburg Forest
ProcedureOpen the START menu. Select any option which opens another screen. Go back to the START menu. The selector will now be a darker red color.
The effect can be reverted by fully closing the menu, or by selecting Save then canceling.