I don't know what you mean by that but you can find rare candies somewhere ? I guess ...
you can't get the pokemon off of pokemon black on diamond, but you can do it the other way around.
Stark Mountain
Migrate from Pokemon Sapphire to Diamond then Diamond to Black/White
Train your pokemon.
yes.go to fuego ironworks and train in the grass
Cheat.
No you can't trade with black to diamond but you can trade from diamond to black using the poketransfer lab. (you will have to have beaten the game before you can use the poketransfer lab). Hope I helped this is luke127 signing off.
No.
capture the legendary and train your Pokemon
train your Pokemon to about lv 20
umm.......i think.....you.....TRAIN THEM UP!!!!!!!!
probly at the pokemon leuge