Anybody knows why there is gba slot in ds boxes?

Anybody knows why there is gba slot in ds boxes? ds with gameboy slot List of Nintendo DS games with GBA connectivity · Contents · Advance Wars: Dual Strike · Bleach: The Blade of Fate · Castlevania: Dawn of Sorrow · Daigasso! Band dsobet slot Remove the Game Pak Slot Cover from the Game Pak Slot · With the label side of the Game Boy Advance Game Pak facing away from the Nintendo DS Lite,

dsobet slot The DSi, 3DS, New 3DS and 3DSN3DS variants do not All of them have a built in GBA, since each of them descend technology wise from the GBA

ds slot The DSi, 3DS, New 3DS and 3DSN3DS variants do not All of them have a built in GBA, since each of them descend technology wise from the GBA  It was actually a nice way to keep games that connected with each other together or were from the same series as well Like the Pokémon games,