You use them in the Entralink and get Pass Powers. They vary and the cost as well vary.
There is not such item called "black steel orb".
You give the lustrous orb to Garitina.
No idea. Have not heard of any 'Black Orb', ever, until now.
No. its is like pearl and diamond where you can only get one of the other depending on the version. on Pokemon white you get the black orb so you can get the legendary Zekrom, on Pokemon black you get the white orb so you can get the legendary Reshiram.
you get it from jirachi
I dont think you can even though you get the adament orb,the lustrous orb,and the griseous orb from the shadow triad on marvelous bridge.
It has the same effect as in Pokemon Diamond/Pearl/Platinum: boosts the power of certain types of moves.
i think its 65617 :) (-o-) Pokemon RULES!
In black and white, if you ever get the legendary Pokemon Palkia, Dialga, and Giratina, you can give them the orbs, and they'll be stronger.
when you get the last badge professor jupiner will contact you over the tranxaver and says ... will you go to the nacering city then when you go there the champing and your rivals plus the professor and the professor's dad saids blah blah blah blah and gives you the black orb (depends about the game if you have black white orb white black orb) . good luck
you have to beat the elite 4 and the if you go to marvelous bridge the shadow triad will com and give you the griseous orb for giratina an adamant orb for dialga and a lustrous orb for palkia
its on island 4. but to get there you have to have the rainbow pass then board the vermillion boat port.