eterna city, 1st floor, condominioms
Yes. Start the whole game from the beginning.
The name of the 3rd Episode in Diamond and Pearl was called "When Pokémon Worlds Collide!"
Yes, Pokemon Diamond and Pearl's region name is Sinnoh Region.
the name diamond is so awesome because.. its a very unusual name and its a name after a pearl
in eterna city there is a man who rates nicknames Of Pokemon (traded Pokemon can't be nicknamed)
anything you want
The name changer is in eterna city there will be a sign Which is the old man in the building next 2 pokemart LuciLicious - If the mew is imported from a game or from PokeRanch or somewhere else and wasn't originally the trainer's in pearl/diamond you cannot change the name.
Stand Up
Pearl or Quartz
There are some action replay codes to change your name to Dialga and a couple that have concequences and your name changes to ???? but other than that I don't think you can change it after you start a new game.
Go to Eterna City and go into the building, that has the Name Rater on the sign. Talk to the old dude at the table and he will "rate" your pokemon's nickname and ask if you want to change it. You cannot change a traded pokemon's nickname.
Yes. You can change its name when you obtain it and if you go to the name rater he can change it for you.