A four-minute-long, animated trailer of Pokémon Black 2 and White 2 was leaked on Youtube, due to hacks enabling people to obtain the file for the video-marked private by the Japanese Pokémon Company. However since then, the trailer has been made public, and may be viewed below:
Details shown in this trailer include:
-Bianca giving the Male Trainer and the Rival their first Pokemon.
-The male trainer preparing to battle Elesa with his Emboar, who after 2 years has a new design and outfit (with her sporting longer, black hair). Her Zebstrika remains a part of her team.
-Cheren, the Rival (with a Samurott), the Male Trainer (with an Arcanine), and Cheren (with a Stoutland) being confronted by Team Plasma on ship, with the latter having new designs involving darker colours and masks which obscure part of their faces. (Given that Cheren is the first Gym Leader in the game, with only a Patrat, this scene seems to support the possibility of re-battling Gym Leaders later with stronger teams. Or at the very least, Cheren, as he evidently used much weaker Pokemon than are in his possession when first battling the player in-game.)
-The Male Trainer chasing a member of the Shadow Triad with his Lucario, only to have their attack blocked by a Bisharp, after which the entire Triad appears, with the one who was chased saying they will accomplish their goal at all costs, whilst holding a container of sorts.