You may use the following tool to introduce dream world pokémon into your black and white/black and white 2 savegame. It has a "legit" mode, in which you directly select those pokémon that were available in Dream World, taking into account the region too (i.e. jap only releases can't be put into non-jap savegames). Of course, it's easier to download the pkm files and edit them (if needed), as theSLAYER suggested, and don't require the BW/BW2 games at all, as you seem to be interested in having them on gen 7.
For dream radar pokestock has an editor, but it is in japanese (I should investigate and make an editor for this too...)