The games take place two years after the events of Pokémon Black and White. The Unova region appears to have changed significantly. New locations are accessible in the southwest and northeast of the region, one of them being Aspertia City, the player's new hometown, while a few previously existing locations such as Challenger's Cave are not accessible anymore. New Gyms and Gym Leaders are also introduced, and the Unova Pokédex is expanded to include Pokémon foreign to the region, much like in Pokémon Platinum.
The player is able to choose to play as the boy Kyouhei, or the girl Mei, as they travel across the region against their rival, Hugh.
Changes from Pokémon Black & White
The opening is drastically different from the one in Black and White, now featuring the new game characters, the Tao trio and the legendary musketeers. Also, the title screen shows either Black Kyurem or White Kyurem, depending on the version.
The bar that shows a Pokémon's level, Exp. Points and HP has been redesigned. It is black in Black 2 and white in White 2.
The area eyecatch has also been redesigned and shows the location in the top left of the screen and season in the bottom right. It is black in Black 2 and white in White 2.
New locations such as Aspertia City, Virbank City and Floccesy Town have been added to the game.
New characters are introduced, such as Hugh, Colress, Roxie, Marlon and Banjirou.
Cheren, Bianca, Elesa, Ghetsis and Iris all receive redesigns.
All Unova gyms receive redesigns.
Most of the Black and White music has been slightly remixed, in addition to the Gym Leader and Champion music from Kanto, Johto, Hoenn and Sinnoh.
There have been several changes made to existing locations, such as Driftveil City and Nimbasa City.
Every Trainer has their own fully animated sprite. They have more frames, allowing for smoother animations.
Several attacks have received new battle animations.
The battle menu has been redesigned.
The C-Gear has been redesigned.
The Unova Pokédex has been expanded tremendously to accommodate older Pokémon.
It also receives a slight aesthetic change, now having a red background instead of green.
All returning Gym Leaders and Champions receive new sprites. This also applies for the overworld sprites.
Route 4 has changed drastically and also differs between Black 2 and White 2.
Victory Road changed drastically from Black and White to Black 2 and White 2 as well and differs in appearance between Black 2 and White 2.
Challenger's Cave's entrance collapsed while Route 10 was locked off due to landslide on Victory Road, making both areas inaccessible. In place of Cold Storage there is now the Pokémon World Tournament.
Places marked on map with green dots in Black and White are now marked with green squares.
The player no longer starts in Nuvema Town, instead starting in Aspertia City.
Instead of the usual 5 Poké Balls, the player is given 10 at the start of his or her journey.
Chili, Cress, Cilan, Lenora and Brycen are replaced by Cheren, Roxie and Marlon as Gym Leaders.
Bianca gives the player a Starter Pokémon.
A new Team Plasma has formed, and is run by Ghetsis.
Colress, a Team Plasma member, is battled frequently throughout the story.
Rood, Zinzolin and the Shadow Triad are battled as part of the story.
The Gym Leader order has changed to Cheren, Roxie, Burgh, Elesa, Clay, Skyla, Drayden, Marlon.
Iris is the new Champion of Unova.
Ghetsis returns and plans to freeze Unova with Kyurem.
N returns to Unova with either ZekromB2 or ReshiramW2, who is then fused with Kyurem to form either Black KyuremB2 or White KyuremW2.
Unlike Pokémon Black and White, the version mascots Black KyuremB2 or White KyuremW2 can't be caught within the story, but can be obtained post-game by following certain requirements.
Cobalion and Virizion interact with the player, making it possible to catch them during the storyline, although it is possible to catch all three Pokémon including Terrakion.
Several tag battles take place throughout the game: one with the other player character, two with Cheren, four with Hugh, one with Bianca and a daily tag battle with one of Chili, Cress or Cilan (against the other two).
A new attraction known as the Pokémon World Tournament opens up in Driftveil City, where the player battles Gym Leaders and Champions from all five regions, among others.
Another new attraction introduced is the Pokéstar Studios, located in Virbank City, where the player takes part in many different movies. Brycen and Sabrina appear here.
Lenora revives the player's fossils.
Several new key items exclusive to Black and White 2 are introduced.
During the post-game, the player may find N at his castle and on the first visit, battles his ZekromB2 or ReshiramW2, who is free for capture after defeating N. Subsequent battles can be done once a season and feature N using a team of Pokémon centered around that season.
The new Unova Link is introduced, which makes way for new features.
Challenge Mode and Assist Mode are introduced, which raise and lower the strength of opposing Trainers respectively.
A new feature called the Memory Link is introduced, which has flashbacks from the NPCs that shed light on events that happened between Black and White and Black 2 and White 2.
Many TMs and all but one HM are received in different locations.
The Xtransceiver adds two new mini-games called Balloon Catch, where the player needs to catch balloons of their face or an NPC's, and Balloon Smash, where the player needs to inflate the balloons as large as possible without bursting them.
The Move Tutors are back, and as with Pokémon Platinum, they teach most of the moves that were in that game for Shards, but here they all ask for shards of a specific color. They also teach many moves that lost their TM status, such as Dark Pulse, Roost and Stealth Rock.
If the player has used a Repel, after its effect wears off, and if the player has more Repels in their bag, they will be asked if they would like to use another immediately without having to go into the menu.
A number of legendaries from Hoenn and Sinnoh (excluding the Weather trio and Creation trio) can be found in the post-game.
Zorua, Zoroark and TM95 (Snarl), which were previously accessible through Nintendo events only, can now be found within the game without any special requirements.
The Kami Trio are notably the only Unova regional Pokémon absent from either game and must be obtained through the Pokémon Dream Radar and then transferred or alternatively they can be traded from Black and White. The Dream Radar is also necessary to obtain their new forms.