you cant cant
day care
Train them............
raise it to level 59
You get a Pokemon with the ability "Magma Armor"
raise it to level 58 or 59
Raise it to level 25 or higher.
Finish the pokedex and raise all ur Pokemon too the end..i guess. Also don't forget to visit white forest.
Litwick
You don't need them for the storyline, you get them so your pokemon can hold them and raise their stats.
you have to raise zweilous to level 64
well the black ones run faster.. so i guessing the white..
Keep the egg in your party and cycle around for a few minutues