PC
A PC is technology used in all of the Pokémon RPGs. They are found in every Pokémon Center, as well as in any main character's bedroom, in all Secret Bases in the form of a laptop, and sometimes in other buildings as well. Their primary purpose is for storing Pokémon and items.
PC Functions
Bill's PC / Lanette's PC
Every Pokémon trainer is allowed to access a Pokémon storage system set up by either Bill in Johto and Kanto or Lanette in Hoenn. They can withdraw or deposit Pokémon in a series of boxes, allowing them to own more than the six permitted in their team. When a Pokémon is captured and your party is full, it is sent directly to the last box accessed on this part of the PC.
Your PC
Rather than having to access a community database, item storage is done on your personal computer. The system is a bit simpler than that of Pokémon storage, and does not have multiple boxes to organize items. Also, unlike Pokémon storage, when you find an item but your item pack is full, you cannot have it automatically sent to this part of the PC.
Hall of Fame
Main article: Hall of Fame
This function only becomes accessable after defeating the Elite Four. It shows records of past victories over the Elite Four.
Decorations
In bedrooms and Secret Bases, the PC has a secondary purpose of managing decorations.
In the anime
The PC is not frequently used by Pokémon trainers in the anime, since Professor Oak tends to keep Ash's extra Pokémon at his laboratory, and other characters tend to keep theirs at home. However, it is sometimes used for communication instead of the video phones; for example, in Beauty and the Breeder, we see that Brock uses e-mail on the PC to keep in contact with Susie.
Nurse Joy and many officials for the Pokémon League and Pokémon Contests are seen using PCs often.