Regions are just composed of maps linked together... There's nothing to it except creating more maps, at a basic level at least. There are however a multitude of problems you won't be able to surmount without advanced ASM knowledge, such as:
1) Limited map names, you'd have to name most of your maps something generic like "Kanto Route" since I think you can have less than like 100 unique names
2) Town map fits 4 regions max
3) limited flying spots
4) it's not just adding "fun" to the grind, you'll literally run out of levels for the player's pokemon to grow unless you dramatically slow growth rates which comes with other problems
5) Probably a bunch of other stuff I'm overlooking
Not to mention it's a massive amount of work, If I were you I'd tone down my ambition and try to make a single region hack first to get a feel for how hard it is.
Thanks. I'll try following your opinion, trying to test lots of things here and there. But, I will not back down on creating a huge hack. Since i got stuffed up ideas on this, i think it's a waste not to pursue it.
I know how massive amount of work it is. I tried starting and yeah, this thing is pretty difficult. I'm just asking if it is actually possible through advanced skills. Seeing your statement, I think I've got the answers I need. I got all the backup I need just being here and I'll make myself a way if there isn't anymore. I don't plan to spend my whole time hacking rather it'll just be on my free time. It'll take more than a year doing it alone, since no one's interested to work with me and i don't mind it. Anyways, thanks for tending to my question sir. Good Day/Night.