Like all the previous games, Pokémon Black & White features a variety of characters who will crop up throughout the game.

Professor Juniper (アララギ博士)

US Name: To Be Confirmed
Jp. Name: Professor Juniper (アララギ博士)

First Appearance: Pokémon Black & White

Details:
Professor Juniper is the Professor of the Unova region. Living in the same town as you, Cheren and Bianca, she will give you a present for you and your friends containing your starter Pokémon in addition to the starter Pokémon for Bianca & Cheren.
After you have got your Starter Pokémon, she will request for you to see all the Pokémon within Unova. She'll crop up through the game to give you advice

Makomo (マコモ)

US Name: To Be Confirmed
Jp. Name: Makomo (マコモ)

First Appearance: Pokémon Black & White

Details:
Makomo is one of the friends of Professor Juniper and will help you at various points in the game. As a researcher, she is deeply involved within the Pokémon Global Link and will even give you the C Gear item

Cheren (チェレン)

US Name: To Be Confirmed
Jp. Name: Cheren (チェレン)

First Appearance: Pokémon Black & White

Details:
Cheren is one of your childhood friends and will receive a Starter Pokémon from Professor Juniper at the same time as you. Starting on his journey, he will appear throughout the game, giving you advice where needed and will challenge you to battles quite often to keep your skills fresh.

Bianca (ベル)

US Name: To Be Confirmed
Jp. Name: Bianca (ベル)

First Appearance: Pokémon Black & White

Details:
Bianca is one of your childhood friends and will receive a Starter Pokémon from Professor Juniper at the same time as you. She also starts her journey at the same time as you, despite the protests of her father. She is a bit unreliable and will not crop up at the right times, but will still turn up and challenge you at a variety of occassions.

N

US Name: To Be Confirmed
Jp. Name: N

First Appearance: Pokémon Black & White

Details:
The mysterious trainer, known only as N, will appear throughout your journey, challenging you to battles. He has a view that Pokémon are friends and should not be used in the manner they are. He wishes to seperate Pokémon and Humans and is looking for the power in order to make his idea occur.

Geechisu ゲーチス

US Name: To Be Confirmed
Jp. Name: Geechisu ゲーチス

First Appearance: Pokémon Black & White

Details:
Geechisu is one of the executives within Team Plasma. There have been numerous images of him in cutscenes grabbing the crown. You first meet him in Garaku Town where he is running a speech to the locals about how you shouldn't enslave Pokémon. The full extent of his involvment is not yet known