When you have a Pokémon with Cute Charm in front of your party, then (if this works, which is completely random because you don’t know your Secret ID) the Pokémon you find of the opposite gender and certain natures will always be shiny no matter what. If you’re okay with hacking, I’m pretty sure there’s a setting on action replay that allows you to see your Secret ID as your money count. Your Secret ID needs to be as close to your Trainer ID as possible.