First, you have to get all 6 sages that are hiding, while your doing that, after you get one sage, looker comes and says that the seventh sage (Ghetsis) is notwithstanding, which means that Ghetsis is not arrested yet, so you have to find him either by beating the elite four again, or finding him behind the trees in white forest/black city.
you can't find ghetsis. i think looker already arrested him, but you can't find ghetsis.
he goes with ghetsis
You have to beat the elite four. Then beat Ghetsis and N.
you go to vantain island you get there after you beat the main story from a ship
You have to catch Reshiram or Zekrom [depending on the version] beat N and Ghetsis and it will be open, but to do this you have to beat the Elite Four.
Bring a Scrafty.
Really after you beat the game, Fight N and Ghetsis, Ghetsis actually gets arrested. Yep. That's pretty much how it goes.
you can't find ghetsis. i think looker already arrested him, but you can't find ghetsis.
You will fight Ghetsis after you beat N
you fight ghetsis
he goes with ghetsis
beat n then you have to battle him
In the dreamyard after you beat N and Ghetsis.
You have to beat the elite four. Then beat Ghetsis and N.
you can catch it in giant chasm after you beat N and ghetsis.
Ghetsis is at N's castle after you beat N After that, he is nowhere!
Beat the Elite 4 and N and Ghetsis. Basically, beat the game.