Help with modding pokemon shield

Recently I have been looking at some pokemon sword and shield mods and i want to know how I can create my own. I know that you cant exactly do anything you want but I know you can replace a pokemons model, rename moves and change their power, accuracy, typing etc and do the same thing with abilities but I want to know how I can actually do all of that. I dont have a jailbroken switch but I have the yuzu emulator. Any help is appreciated!