Gen V gives you the option to Migrate from Gen IV Games. But how would that work, because it is 2 DS cartridges and only one Slot(there was a DS and a GBA Slot for Gen IV Migration)?
You need 2 DS/3DS consoles - i.e. any 2 of: DS, DS Lite, DSi, DSi XL, 3DS, 3DS XL.
Then DOWNLOAD Pokémon from IV gen to V gen. They may not have HM moves (but can have Whirlpool from DPPt and Defog from HGSS) and items.