The bag is quite possibly the most useful item in many of the Pokémon games. It is the item 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.

Generation I

Originally, all items in the bag went in the same pocket. 99 of any one item could fit inside, with only a certain number of items allowed in the bag in total. When the bag was full, the main character's PC could be used for any sort of item storage.

Generation II

With the second generation of games came a major change in the bag's design, with items being separated into four pockets based on their type.

• Healing items, including berries
• Poké Balls
• TMs and HMs
• Key items

Generation III

In the third generation, there was a visual of the bag as it was searched through, with different bag designs for the different characters. This generation also expanded on the pocket system from Generation II, with five pockets instead of four.

• Healing items
• Berries
• Poké Balls
• TMs and HMs
• Key items

Pokémon FireRed and LeafGreen

The pocket system was different in these games. Rather than have separate pockets for berries and TMs, the key items pocket contained two sub-pockets, the TM Case and Berry Pouch.

In the anime

Most important characters in the Pokémon anime have a bag, and usually keep their supplies and Poké Balls inside of it. Brock carries many more items in his bag than the other characters, including a variety of healing items, books, and cooking supplies, and his 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.