White and Black is a flashback of two Plasma Grunts talking in the topmost house of Hodomoe
City (not sure what to call it), about what to do, now that N has left. #2 wants to go to another region and join another evil syndicate but #1 calls him an idiot many times over, saying that everything they did was for the sake of Pokemon. They eventually decide to go to N's abandoned castle and start looking after the Pokemon left there to care for them. (it's not stated, but I assume this is what starts Ex-Team Plasma) After they leave, N reveals himself from where the Goddesses were in B2W2, and monologues that he was right there, listening. He wonders how everyone is doing, but decides that he must leave Team Plasma, for both humans and Pokemon, to do a task only he can, to convey the emotions of Pokemon to humans.
Whose flashback is it? Who knows. You enter the house, Zoroark
looks at you and roars, and the flashback starts.