How can you find shiny Pokemon in emerald?
Its random to find shiny Pokemon you have a 1/8000 chances to see one if you want to find a certain Pokemon shiny stay in the area of that Pokemon where either you can find it all the time or most of the time: For Example: Stay in Artisan Cave to find a shiny Smeargle.
Yes it takes 1 out of 8000 chances to find a shiny Pokemon all you need to do is look for wild Pokemon for a long time eventually you will be lucky. Trust me when i say you can catch a shiny Pokemon because i have done it myself it happened to be a shiny shuppet which i found on the route west of lilycove city.
Pokemon are determined to be either shiny or normal when you first meet them either when they hatch from their egg or you see them for the first time in the wild. Since charizard do not appear in the wild naturally in Emerald, you will need to hatch a lot of charmander until you find a shiny one. After that you just need to evolve that charmander into a charizard.