First off, thanks a lot for this tutorial! I am having some issues here, though, I hope someone will be able to help - I'm not sure what exactly I'm doing wrong, so I'm gonna go ahead and specify what I've been doing - sorry if this is a bit frowned upon, I don't often post here, and sorry if I'm going into too much detail, I just wanna be thorough, because I have no clue what I'm doing wrong. I've only gotten as far as completing step 1, but the game crashes right after the intro-battle-video thing stops.
Firstly, I'm starting off with MrDollSteak's Decap & Attack Rombase, so it's not like I'm making things easier for myself, I guess, with new pointers and offsets and whatnot. Mind you, I'm still pretty new to hex editing, but I think I understand the basics.
Anyway, as for finding the image in the first place, I'm pretty sure I'm supposed to use the one located at 961C00, because where (in an unmodified ROM) I would normally find the pointer DC5DE908, I found 001C9608 - and NSE supports my theory, it seems:
I edited the height to 18 before exporting, made my new type graphics and (succesfully?) inserted my new image at the offset 96571C. Then, I went back to the pointer 001C9608 and changed it to 1C579608 to match my new offset. So far, so good, the game doesn't crash or anything, when I open it at this point, and the type icons show up okay. (not the two new types, I didn't test for those, as I figured they weren't really implemented as icons for any type yet) Here's the image I inserted, I didn't change the palette, and I only used colors I could already find in the image I exported:
Now, this is where things went wrong - apparently. Like with the other offset, here I went to 96197C instead of 452C94 by looking at the pointer that I'm later told to edit. So, I go to 96197C, select 64 blocks instead of 60, because MrDollSteak has already added the Fairy type, and the last 4 of those 64 bytes clearly seem to be the Fairy type. So I copy those 64 bytes and insert them at 967B1D, right after where I inserted the image, with only a few bytes of free space between them. Then I add the bytes for Digital and Cosmic at the end of the table (20 0C AC 00 and 20 0C 08 01, respectively) and finally, I find 7C199608 and replace it with 1D7B9608.
And NOW, the game crashes on start-up. Also, upon further inspection, something now seems to be wrong with the image I inserted. This is the offset where I inserted it, and this should still be the same palette, but the colors are clearly all wrong: