Go to a Pokemon center to make space for the egg then go back and they will still be there.
You go to a Pokemon center.
Pokemon Diamond? If so yes there is.
There is no space center, that is in ruby, sapphire and emerald.
In Hearthome, next to the Pokemon Center.
Get a Graveler and trade it in any Pokemon center
Woman in Eterna Pokemon center.
North and west of the Pokemon center!
in platinum she is in the Pokemon contest center
the trade center is up stairs in the poke center
The Pokemon day care is in Solaceon Town