I made some, and will make what I can but if there are other places where these exist that would be nice to know so I don't repeat the effort.
Stuff that I made (light green) Stuff that's perfect as is but not mine (dark aqua) Stuff that will work, but it's sloppy (purple) Kanto (FRLG):
Raw map: https://zyga.feen.us/zf4jzrl208.png ( https://www.deviantart.com/rythos/art/LABELED-Map-of-Kanto-201763600 )
Entity Map: https://zyga.feen.us/pujlb7q79q.png
Pokemon Map: TBD Kanto (Sevii Isles):
Raw map: https://zyga.feen.us/h3z1o8kpwu.png (unknown source, from /v/)
Entity Map: https://zyga.feen.us/dkm3xti0oj.png
Entity Map with Extra Notes: https://zyga.feen.us/fule8omcqw.png
Pokemon Map: TBD Kanto (HGSS) (not in pokeMMO yet):
Raw map: https://zyga.feen.us/4fk7yyum91.png (unknown source, from imgur)
Hidden Items Map: x
Pokemon Map: x
Johto (HGSS): (not in PokeMMO yet)
Raw map: https://zyga.feen.us/z4rfb7z2jl.png (unknown source, from imgur)
Hidden Items Map: x
Pokemon Map: x Hoenn (Emerald):
Raw map: https://zyga.feen.us/zlk0hrry8d.jpg (RUBY/SAPPHIRE) ( https://www.deviantart.com/jay21310/art/Hoenn-Overworld-Map-31344982 )
Ultimate Entity Map (Pokemon, Interiors, hidden items): https://zyga.feen.us/mvc081wm1x.png
Sinnoh (DPP): (not in PokeMMO yet)
Raw map (with trainers and visible items): https://zyga.feen.us/5swa1vd6le.png ( https://www.deviantart.com/galifiastudios/art/The-Sinnoh-region-birds-eye-view-584570068 )
Hidden Items Map: x
Pokemon Map: x
Unova (BW):
Raw map: https://zyga.feen.us/p2yudzappc.png
(incomplete and for BW2, but better than nothing: https://www.deviantart.com/galifiastudios/art/What-Unova-Really-Looks-like-WIP-713463243 )
Entity Map: x
Pokemon Map: x
Kalos (XY): (not in PokeMMO yet)
Raw map: x
Entity Map: x
Pokemon Map: x
The 3D maps will take much longer to make as they require a lot more effort to make them into a top down image with proper textures, along with adding entities.
Not All maps will be accurate with PokeMMO since it changes some things like NPC positions and what items are where. Even with that though these can still be useful.