If you are referring to a man dressed in green who hands out mystery gifts, he is not set in any specific city. In fact, unless you have Pokemon Battle Revolution for Wii and a fair number of points,...
Pokemon cannot be transferred from Diamond to Leafgreen. This can be done backwards, however as Ruby, Sapphire, Emerald, Firered, and Leafgreen Pokemon can be permanently transferred to Diamond,...
To trade Pokemon from leaf green to diamond, you have to see every Pokemon in diamond then you go to professor rowan and get the national pokedex. then insert the leaf green game and turn off then...