The bag is quite possibly the most useful equipment in many of the Pokémon games. It is the equipment which holds almost all of the main character's other items. Even bikes can fit inside it, which later generation games explain by saying the bikes are collapsible.Still,Generation I is the most realistic,for example,you could not possibly fit berries into a bag with a bike (even if it is collapasble) without being crushed.also it is inpossible to have infinite items such as in Generation IV

Generation I

In Generation I, any item placed in the bag were in the same pocket. Ninety-nine of any item could fit inside, with only twenty different items allowed in the bag in total. When the bag was full, the player's PC could be used for any kind of item storage.

Generation II

In the second generation of games came along a major change in the bag's design: Items could now be separated into four different pockets depending on what they are.

Generation III

In Generation III, the player could get a visual of the bag as he or she searched through it, with different designs of the bag for the unique characters. The amount of a single item that a player could carry was also expanded to 999, though if this limit is reached, they can still carry more of that item as it simply takes up a second slot in the bag. This generation also expanded the Pocket System from Generation II, with five pockets instead of four.

Pokémon FireRed and LeafGreen

The Pocket System in these two games differed from the rest. Rather than having separate pockets for Berries and TMs, the Key Items pocket contained two sub-pockets, the TM Case and Berry Pouch. FireRed/LeafGreen also introduced images for the items, the first time they had been pictured in the games. This feature was kept in Pokémon Emerald (though it was crudely added to the same menu structure as Ruby/Sapphire's bag system) and continued on into Pokémon Diamond and Pearl.


Generation IV

Generation IV revolutionized the Pocket System even more, dividing the bag up further:

The player can navigate the bag by either using the face buttons on the DS or using the Touch Screen to scroll through the bag and items.

Unlike previous Generations, the bag has an infinite amount of space within it, meaning that the PC Item Storage system is obsolete and not present in the 4th Generation. It is replaced within the PC menu with an option for decorating Poké Balls with Seals instead.

Key Items can still be set to a hotkey that the player can press to call on that item without going through the bag each time but instead of the Select button - as has been the precedent in the past two Generations of games, this has been assigned to the 'Y' button.

In the anime

The major characters in the Pokémon anime own a bag and usually keep their supplies and Poké Balls inside of it. Brock seems to carry many more items in his bag than the other characters, including a variety of healing items, books, and cooking supplies. Brock's bag seems to best reflect the impressively large capacity of the game's bag. In The School of Hard Knocks, he pulls a table and full tea set out of his backpack.