I don't understand why Alder and/or Cheren would be searching for Ghetsis. It's not like they are the police. Any arresting from them in BW1 I assumed was like a citizen's arrest...Also, speculation as to the fate of past chartacters:
Hilbert/Hilda: Pulled a red or has taken over Alder as current champoin
Cheren: Wanderer or Champion or maybe with Alder investigating where Ghetis is
Bianca: Junipers assistant, no question
Alder: Pulled a red, still champoin or with Cheren investigating the whereabouts of Ghetis
N: Turns up at the begining of BW2 with the Dragon on the front cover
Ghetis: May or may not show
Shadow Triad: Again, may or may not show, may or may not be Striaton trio
Iris: New Opelucid Gym Leader in both versions
Drayden: New champion?
Perhaps N is searching for Ghetsis though?
I don't think he necessarily has to be in the sequels btw. It's quite possible he released his dragon. It's not like that wouldn't fit with his personality.
And I honestly would be a bit ticked if Drayden became champ. I would accept it after a few minutes, but he really played no role in the first game and moving the 8th leader up out of left field like that is something I hope they wouldn't repeat. I'd rather have a double battle with Iris and Drayden for the 8th gym battle.
.....
I think it would be cool if the player's mom played a big(ger) role in the sequels. Gold/Crystal's mom functioned as a bank and Lucas/Dawn's mom participated in contests. A useful mom would be interesting. At least give us one strong parent...