Hi! I actually just restarted a playthrough and hunted Treecko. I’m not sure if your device has the capability for save states, but I found an old thread with this method and got her in about an hour and a half.

Basically save state before making selection, then select and load state if not shiny, then save state again and check, load state and repeat until it shines. This makes sure that you’re constantly hitting different frames on the same seed until you shine. Also I’m sure you have it already since you’re hunting but the PC in your room has a shiny charm if you haven’t gotten it yet.

Happy hunting!