You should honestly change how movement permissions are shown. While most map editors act like it's the upper 6 bits that determine collision, e.g.
Code:
struct MapTile {
u16 tile : 10;
u16 permission : 6;
};
It's actually more,
Code:
struct MapTile {
u16 tile : 10;
u16 obstacle : 2;
u16 height : 4;
};
When the obstacle bits are 0 the tile is passable, when they are non-zero the player's passage is blocked. I honestly have no idea what the values 2 and 3 are for because I've never seen them explicitly used (they seem to be treated exactly like 1), but 1 is typically used to indicate that the tile is impassable on its height.
The height bits are used to block the player from climbing cliffs. 3 is the default height, which is why "movement permission" 0xC is used as the general passable tile.
Heights 0 and 0xF are special cased. Both of these heights ignore the height check. The former is used to apply to all levels (which is why permission 0 allows transitioning heights and 1 is an obstacle on all heights), the later is to allow the player to walk under bridges without changing height (see bridges such as in Fortree City). Height 1 is chosen as the surfing height, but this is only by convention: the actual height chosen is not important and serves only to prevent the player simply walking into the water (surfing is handled by block behaviours, not movement permissions). This makes the waves icon for height 1 very misleading (see spoiler).
It might also be important that a higher value for height does not seemingly imply a higher place. Route
120 in Emerald seems to use a higher value on a visually lower place on the map - all that is required is that the heights differ if you don't want the player to pass through.
I would suggest you split "Movement Permissions" into a height map and obstacle map or something so that you reduce confusion on maps that use varying heights extensively like Mossdeep City or Route 119. Emerald typically has way more variety in terms of mapping features so I think you should probably test your tool out there instead of just on FIreRed.
![Awesome Map Editor _ Pokemon - Fire Red Version (U) (V1.0).gba _ [03, 14] ROUTE 2 11_25_2016 6_2.png](https://data.pokecommunity.com/attachments/4/4883-559de515d5b78a40c3ce3f3a56f400bd.jpg)
![Awesome Map Editor _ Pokemon - Fire Red Version (U) (V1.0).gba _ [03, 14] ROUTE 2 11_25_2016 6_2.png](https://data.pokecommunity.com/attachments/4/4886-559de515d5b78a40c3ce3f3a56f400bd.jpg "Awesome Map Editor _ Pokemon - Fire Red Version (U) (V1.0).gba _ [03, 14] ROUTE 2 11_25_2016 6_2.png")
![Awesome Map Editor _ Pokemon - Fire Red Version (U) (V1.0).gba _ [03, 07] FUCHSIA CITY 11_30_201.png](https://data.pokecommunity.com/attachments/4/4919-e413a3f62ebd0a5edd122876eb561802.jpg "Awesome Map Editor _ Pokemon - Fire Red Version (U) (V1.0).gba _ [03, 07] FUCHSIA CITY 11_30_201.png")
