After you beat the Elite4 and walk throught a bridge(i don't remember the name) three guys show up and give yo the 3 orbs. BUT you cant get Giratina, Palkia, Dialga in B/W except from trading on GTS or from a friend. If you have D/P/Pt or HG SS you can send them to you pokemon white. This can be done ONLY after you beat the Elite4 once. You need 2 ds systems(all ds systems are ok. NOT 3DS), a copy of pokemon Black or White and a copy of D/P/Pt or HG SS. You can search serebii or type poketransfer in youtube.