>>57431572as someone working on their own region, I'd recommend making new maps. I started out mapping over top of old maps but I found that because they have scripts tied to them, it's better to just start from scratch so that you don't run into conflicts.
if you're working with the Emerald decomp, you'll be mapping in Porymap, which is a great and intuitive program. you have the option to make new maps. I'd also recommend making a new "map group" (folders that contain the maps, picrel) to keep yourself organized. you do have to go into the game code to make a map group but it's easy enough. I just poked around one of the decomp discords to find instructions. if you have any trouble, post back here when you get set up, I'm usually lurking and can help out. maybe download Porymap first and try making a map or two just to get yourself familiar with the program.
as for coding, I'm only just getting started on that myself, I was always more of a mapper so I did that first. so far I've only done basic stuff like setting up trainers and adding sprites, I haven't gotten much into events yet. but it's been easier than I expected, there's some great tutorials on youtube and the pokeemerald wiki, and also get on the discords so you can search old conversations, that's been really helpful. I think the main ones are the Team Aqua disc and RH Hideout.
