The Bag is a tool in all main Pokémon games. It holds all of the player's items, storing them until the player uses them. When opening the bag, the player can use, arrange, and toss any items except for key items, and register key items for easy access. All the items that the player has on hand will be located in the bag, after Generation II, being placed in the appropriate pocket automatically. Prior to Generation IV, the Items pocket had only limited space for the items, while the other pockets had space for any and all items that would go there. If an item to be picked up would be placed into the items pocket, however, and the pocket was full, it could not be picked up until the player had deposited some items into the PC. This problem no longer exists in Generation IV, where the bag has enough room for every item. In the bag menu, the player will find a list of all their items, ordered from first obtained to the most recently obtained.
It is hard to find what you are looking for, because the item names are in small letters and one of the easiest ways are looking at the pictures that is, if you know what they look like. Though you can keep anything and as much as you want is an advantage.
It is mostly the same as Diamond and Pearl except the bag now has a different color scheme and more key items.
Items are no longer displayed in a list, but grouped in sections with six items per section. In HeartGold and SoulSilver, there are new Poké Balls that can be carried in the bag.
The items are once more displayed in a list. Items can be reorganized with Select once more, though there is now a button that organizes all items in a section in alphabetical order.