Dual-slot mode
Dual-slot mode (Japanese: ダブルスロット double-slot), often called the dongle method, is one of the many ways that players of Pokémon Diamond, Pearl, and Platinum can obtain Pokémon that are outside of the Sinnoh Dex, especially Pokémon that are exclusive to other regions, by using the GBA games of the series as dongles for the DS games.
The majority of Pokémon that can be obtained in this way are in some way version-exclusive Pokémon to one of the Generation III games. With one of the five Game Boy Advance games inserted into the GBA slot of a Nintendo DS while playing either Diamond or Pearl, players will be able to find Pokémon not otherwise available in Generation IV in certain areas of Sinnoh, but only after they have unlocked the ability to use Pal Park as well. One does not need to have the game in their GBA slot the whole time; one just needs to have it in at the main screen, at which time one can simply take the cartridge out and if the cartridge is borrowed, can give it to the owner, as long as one doesn't turn the power off before catching the Pokémon.
Using the dual-slot mode with all five GBA games and trading version-exclusive Pokémon between Diamond and Pearl, players can get all Pokémon excluding Tangela, Tropius, the starters, and legendaries of previous generations. Platinum removes the need to send Tangela, Tropius, and the legendary birds through Pal Park, and with an event Regigigas, the need to send the legendary golems as well.
Unlike Pal Park, dual-slot mode is not language locked; any language Generation III game can be in the bottom slot for any language Generation IV game, meaning that a Japanese FireRed can activate wild Elekid in the Valley Windworks in an English Diamond, while an English Emerald can activate wild Teddiursa on Route 211 in a Japanese Platinum. Dual-slot mode on the DSi is completely impossible; due to the removal of the second slot to make the unit thinner, there is no way to insert or play Gen III games on the DSi.
All of these Pokémon have an 8% chance of appearing in the listed area when the correct GBA game is inserted.
