ASleepyCat

I've been working on a ROM hack identical to this. Most of the things can be replaced without any problems (the things that are bugged are the trainer card sprite, Elesa's gym MC texture and the bag sprite as far as I know). First, you need a couple of tools first: 1. https://github.com/pleonex/tinke"]Tinke. You'll need this to extract the textures and replace sprites. You're probably running an outdated version, so update it first. 2. MKDS Course Editor. This is for replacing the textures inside the .BMD0 files. Use the Nitro System in the Tools tab when importing the textures. You can also use Every File Explorer, but there's no current stable release yet. 3. This page. This will tell you most of the .narc locations of the files you need to edit. You'll need to find the actual files within the .narcs yourself. 4. Kazo's B/W Tools. You won't really need this, but it'll make the overworld sprite editing process a lot more simpler. As for the XTransciever, there are two files you'll need to replace: the main sprite and the eyes sprite. Replace those and you'll be fine. For the back sprite, there are seven files that are associated with each sprite. You'll need to find those and use them to replace Nate's sprite. Each lot ends at the palette file. You'll need to edit the textures for the intro. For the bag, it's a bit buggy and you need to do some tinkering to make it work. The flying animations are actually a 3D model and, as such, you need to replace the textures in the model. Use Tinke to extract the model and MKDS Course Editor to replace the textures. Before editing a ROM, you should try to understand how the game organizes its data and what to do for any situation.