I'm not very sure about this but search for a boat to see if you can find looker and talk to lots of people in the game cause they might give you hints like legendary locations and where you could find a person important in the game like bianca or the champion who knows the game is full of mysterious?
Chat with our AI personalities
He pops up out of no where and tells you news about N then leaves.
Well you defeat alder and he will register your pokemon on the hall of fame. After that you have to find all seven sages including ghetsis.
i have been on several official cites looking for this including Pokemon wiki and serebii they list how to find the seven sages but not ghetesis so i think you cant sorry
After you have Looker arrest the last sage out of the Seven Sages, He should thank you and he should also tell about a boy who sounds exactly like N, who has been seen with a dragon pokemon somewhere far away... ^_^
he/her is in white forest at level 5 but you have to find all the seven sages then once you have done that so of the grass in white forest will become water. Surf on the water and you will find him soon.