Here's why:
* Shiny Pokemon are determined by game code. The shiny status of a Pokemon is set when it's created within the game's code, not by any external code like an AR code.
* AR codes are limited in scope. AR codes are designed for things like adding items, changing the weather, or modifying certain aspects of the game. They can't fundamentally alter game mechanics like Pokemon shininess.
How to get non-shiny Pokemon:
* Catch wild Pokemon. The vast majority of Pokemon you encounter in the wild will not be shiny.
* Trade with other players. You can trade with other players to obtain Pokemon that are not shiny.
* Breed Pokemon. When you breed Pokemon, the offspring will usually inherit the non-shiny status of their parents.
Important Note: Using unofficial AR codes can potentially harm your game save file or even ban your account. Stick to official methods for getting non-shiny Pokemon!