Okay, so I can definitely see where you're coming from but this is in need of a
lot of work.
Your map is definitely way too small. While browsing through a playthrough of Colosseum to get an idea of the layout I noticed that there's a series of trainer battles that take place near the bridge. There's like 5 NPCs. The map is going to seem extra cramped when the NPCs are placed. It would not be a bad idea to put some placeholder NPCs in when you're designing the map to get an idea of how the player will interact within the space.
The layout is way too boxy. Since you're using square tiles of course it's not going to have smooth curves but you can still simulate curves better than what is currently there. Pyrite Town has a natural feel to it so you need to have that organic shape.
I do not feel the mountainous regions were laid out with enough care. Like, I can see a little thought went into them but there wasn't much attention to detail. Take for instance the mountains next to the Colosseum, on the left side you have a mountain that has three layers, but on the right side it's just one layer, unlike the actual game. And the cave you exit from, if you look behind it there's another layer of mountain that continues upward in-game.
The area under the bridge really shouldn't be purely void tiles. You should have darker mountain tiles that extend downward to imply that the mountains aren't just floating in space. That might seem pointless to mention because it's somewhat obvious, but I mention it because there
does need to be some consideration to how you end up laying out those tiles because the mountains don't suddenly turn into a flat sheet of rock.
There needs to be dirt tiles in front of the lower part of the bridge.
Since this is just a layout I haven't commented on the tiles, but I think I should mention a design element that would be important to consider during the layout process. Pyrite Town is pretty unique in that most of the buildings are at a slight angle. I think it's important to retain that aspect because it adds to the character of the town. I'm pretty certain it would be possible to design tiles that 'look' like they're at an angle without getting in the way of the player's experience.
Another thing to consider, what graphical style do you plan to us? Gen 3 or Gen 4? That will affect the size of your map.
In case you don't have it already,
here's a map of Pyrite Town to reference while you're working.
