there are none that i know of in diamond. sorry(-_-)
No. In Pokemon Diamond you can only catch Dialga once but you MIGHT have a second chance after beating the Pokemon League at least once.
The charcoal item in Pokemon Diamond powers up your attack by 20%.
Actually, yes you can. South from where she is there's a hidden key, you have to use the item finder to get it.
The amazing and exotic surfboard which can be obtained as an invisible item in sandgem beach. When you give this item to a Pokemon it can learn surf and if you take the item from the Pokemon it immediately and abruptly forgets the hidden machine surf
The Special Key is a key item in Pokemon Diamond. You can find this item in a warehouse in Veilstone City.
The Magmarizer is a held item in the Pokemon games that helps the Pokemon Magmar evolve into Magmortar. This item can be found in Pokemon Diamond held by Magbys in the wild.
The dawn stone is an item that is used to evolve certain Pokemon in Pokemon Diamond. To get this item, search in Mt. Coronet.
knowa
You have to get to the middle of the turn back cave (available after beating the league, where giratina is in Pokemon diamond and pearl), and there will be an item and a portal to it
yes
It will keep the item cause the Pokemon is being migrated and like in the wild how the Pokemon sometimes has an item it is the same in Pal Park.
no there is not sorry