If anything it's easier to map something that's already been made.
And actually, people make maps from other games all the time. There are about a thousand remakes out there.
So you mean none that you have seen.
You can't just take somebodies fakemon and put them into a hack, they're someone else's artwork. That's plagiarism
Also, you should try researching with the ROM to find a way to script. Since it's a R/S/E remake it won't be the same without maps either. :\
Someone is working on a map editor...
leo @'d me in a thread about his last dream, stating he was passionately making out with a guy he used to know and then woke up while reaching for his crotch, and said that i would "know who 'tf' it is"
and of course i know, it's luke