Multi-player and single-player maps are vastly different. If you want to eventually make this map a multi-player map terrain it as though it is one, it is a royal pain in the ass to delete resources /re-terrain everything/move regions/re-assign triggers after you have decided to change the player count. HC has a point with reducing the doodad size to, he has been making models incredibly small sizes so that the map can still function the way it ought to, and if this map were to have a large store of imported materials it should be the pokemon models, not all the fancy doodads. It's not like people are going to play this map or the regular games for breathtaking environments and incredibly detailed locations anyways, the winning factor for the game is the gameplay. While blizzard doodads look worse than UTM ones, they look infanently better than the mystery barrel/bush/tree? environments from the gameboy. So go through the imports and delete the ones you don't need, and as HC said only the textures may cause problems, you can delete an unused model with no trouble at all.
On a side note, what are you guys planning on doing for the trainers? In R/B/Y there are around 15 different types of trainers with a different in-game sprite, and the elite four and gym leaders as well. And each new introduction to the series just keeps increasing trainer variety. Are you going to have a handful of generic trainer types that use the same models? Will you go for different trainer types but re-use models for them or use various humanoid models to fit them? Or are you going to import custom models/skins for a variety of trainers and gym leaders? As far as planning what new models to do for the game it should at least be considered. Anyways, mostly thought about that as an issue concerning space and file-size, even in maps were I work with the space given and try to refrain from going overboard with resources file size always catches up, and fast.