You find him in the plasma frigate in 17+18+P2 Labratory area
You find it in N's castle after you beat the elite four.
you can find it in black city after you find the seven sages and beat the elite four and the champion
Looker will give it to you after you beat Ghetsis, i.e., after elite 4.
The elite four, the champion, (Cheren, Bianca,you have to find them)and,(Cynthia,after you beat the game)
u can beat it! u have to kill the elite 4 then u find all the sages, then u fill ur pokedex and fight every trainer.
after you beat the elite for the ferry is complete and captain stern is the captain of the ferry (i think check to find out)
he stays in the elite four as champion
you must once more beat the elite 4 then the spot will gloe you go there!
nwhere its impossible to find him UNTIL you beat the elite four again
after you beat elite four you will go to N's castle and get to catch reshiram and fight N. you can get another on top of the dragonspiral tower.
You beat the Elite Four once. *SPOILERS* Go to the Champion and you go to N's Castle, Zekrom (or Reshiram if you playing Black) will be there.
After you beat the elite four, there's a zoarak out side victory road . Follow that zoarak and he will lead you to n , n gives you the black stone in pokemon black , and the white stone in pokemon white. Get the stone to dragonspiral tower and it will revive. Catch the legendary pokemon and then find kyurem in giant chasm. Before you beat the elite four, you will have to beat white/black kyurem after you beat it, there's the gene wedge on the floor.use that gene wedge to fuse reshiram/zekrom to kyurem to get black/white kyurem.