Wrong. Diamond and Pearl don't use 32 by 32 tiles.
They aint near that size. They are bigger then the traditional 16 by 16 used by the advanced games, but not 32 by 32 pixels. The characters are only 17/18 pixels in width anyways- and since pokemon uses a grid based system for movement, there is no way that any tiles are 32 by 32.
I didn't mean that the D/P tiles (or grid) were 32x32, I meant that each world map square is 32 by 32 'tiles' (or takes 32 steps to travel across). Anyway, I now realise I was wrong, and the actual map chunks loaded into memory are 16 tiles wide, by 16 tiles tall. D/P textures still use 16x16 tiles; while the OWs have become bigger, the actual textures are still the same. If you stand next to an NPC, then your sprite overlaps theirs.
Alexandre, if you use whole images for maps, then you'll still use up a lot of RAM... 16-color images wouldn't work with the large number of colours used in a tileset, so I'll assume your maps are 256-color images. Therefore, each pixel takes up 1 byte. Assuming a typical map size of 32x32 tiles (or 512x512 pixels), each map would take up 256 KB (512x512 bytes) of memory. Since you have to load the maps surrounding the map your character is standing on too, the typical number of maps in memory will be 3 or 4. That's already 1/4 of the DS's memory used up. If you include a second layer (for treetops, housetops etc), then that doubles to half of the DS's memory. So you've used up half your memory on merely displaying four maps. If you're in a place with more maps near it, such as Hearthome City (you'd have to load 6 32x32 maps at once), or have other things such as weather and particle effects eating up memory (if you decide to use them), and you're probably going to find yourself running out eventually.
If you use tile-based maps, you only have to load a tileset image, which is a few KB at most, and the tilemaps for the on-screen map, which are even smaller. It's a much more efficient method. I think that if you make an attempt to script a tile-based system now, you won't regret it later. Maybe you could try coding something else, such as the battle system, first (to build up your experience)?
Surely you could make an RGSS script to convert RMXP maps into arrays usable by DS Game Maker? The RMXP map format isn't very hard to understand...
