Yes
Use items or go to a Pokemon Center to heal your Pokemon.
Item BoxesYou can't store items in Pokemon Diamond and Pearl. The Item boxes were only for the older games. Now, to store items, you can just give the items to Pokemon stored in the PC.
Get a Pokemon like zigzagoon and just walk around. Make sure it is not holding any items. Then when you walk around, check your pets holding items after about 30 SECS, and there should be an item there :)
In the Pokemon Center, at the end of the desk. Then select the top choice. From there you can do various things, like deposit Pokemon, withdraw them, move items between Pokemon or remove items and put them back in your bag.
You find items that can be sold to a collector in Lacunosa Town.
You battle trainers and buy items. You can invite people to it when you're using the Entralink, and this will increase the occupancy of the city, and improve the items that are sold there.
Sell find items, in the description it might say "can be sold for a high price"
If you mean items you sold, go to My eBbay.
Items sold at Concorde Memorabilia include on board items, gallery items, and engineering collectibles. You can check out these items directly from their website.
There are many items that are sold at the Clothing Warehouse. Examples of items that are sold at the Clothing Warehouse includes shirts, jackets, jeans, and dresses.
You can only breed pokemon, not items. Items aren't alive!
In a way, yes. You can give items to your Pokemon and trade them.
no but you can trade Pokemon holding the items.
It contains the element plate items, as well as Relic items, which can be sold to the relic maniac in the Undella mansion. The item at the bottom is the Relic Crown, the most expensive.
Cant you can only on Pokemon heartgold search for how do you clone items in Pokemon heartgold and my answer will be there
You can clone items in Pokemon Ruby. You can accomplish this by attaching the item to the Pokemon you are cloning.