He is not in ecruteak city he is in goldenrod. You can find him by going In the path in between The Pokemon center and Game corner. He is in the oarnge house. He will give you an eevee when you find him.
bill gives you it i n heart throme city
Blackthorne city is not in Pokemon Diamond but in Pokemon Heart Gold/Soul Silver
Bill's relatives live in Goldenrod City, and if I recall correctly they live on eastern side on the path to the bike shop.
In the Pokemon center in ecruteak city When you enter the ecruteak city Pokemon center bill will come down from upstairs then he will return to his house in goldenrod city
If you are referring to Bill, the guy in Cerulean City of Pokemon FireRed and LeafGreen, he isn't in Pokemon Pearl. There is another person, that does the same job as Bill, named Bebe. Her house is next to the Pokemon Center in Hearthrome City.
He is in Goldenrod City.
Aliza town
Heart Home City.
Go to pewter city and feed your Pokemon lemons from the tree in the city square
you get it from bill in goldenrod city
it should be in olivine city
The Pokemon Fan Club is in Vermillion City.