I think this is notable enough to mention here
It is not possible to trade Pokémon stored in the [[PC]] in these generations, so they must be placed in the party prior to speaking with the receptionist at a Pokémon Center.
Generation IV's [[Global Trade System]]
utilizes a separate trading process, in which a player deposits one Pokémon at a time (requesting another Pokémon in exchange) and other players may search and trade for it at their leisure. Once traded, the original player will receive the Pokémon upon logging in to the GTS. If the Pokémon is not traded, the original player can cancel the offer by withdrawing their Pokémon from the GTS.
Players registered on each other's [[Pal Pad]] can communicate with live voice chat during the trade. A set of four emoticons (Smile Mark, Saddened Mark, Heart Mark, Surprise Mark) also allows for limited communication between players. In addition to showing the Pokémon on offer, the top screen also includes an abstract glimpse of the other player's Pokémon collection in the form of PC boxes with individual Pokémon represented by their [[List of Pokémon by color|Pokédex color]].
The GTS, in addition to the deposit/search-based system introduced in Generation IV, receives a second trading mode ("GTS Negotiations") allowing two players to connect and trade Pokémon using this system.