Story: The story is the same as the original Sonic Adventure 2 game.
Levels: The levels are the same as found in the original Sonic Adventure 2 game.
Chaos Emeralds: No changes have been made with the Chaos Emeralds from the original Sonic Adventure 2 game.
Miscellaneous: Sonic Adventure 2 introduced a new two-player versus mode. SA2B takes the versus mode and expands it, giving the players access to a total of 12 players. The extra six characters were originally unlocked by obtaining all A-Rank for each main character (but now getting all A-Rank unlocks that character's alternate costume). In Sonic Adventure 2, these new characters made little or no noises, so SA2B adds extra elements to these characters. SA2B also unlocks a new character for kart racing when all missions for a character are complete (in Sonic Adventure 2, completing missions would unlock a new costume).
Green Hill can still be unlocked, just as in Sonic Adventure 2. However, there are different emblems to earn in order to unlock the zone. The new emblems are mainly from Chao Karate. There is also a new all A-Rank for Cannon's Core, which wasn't included in the Dreamcast version. Even though there are a few adjustments, the total number of emblems still adds up to 180.
A lot of changes for Chao were introduced in SA2B. Instead of the Dreamcast VMU appearing in the Chao Garden (for the Chao transporter), there is now a Game Boy Advance. Chao can be taken from the GameCube and placed in a Tiny Chao Garden (which is in a Sonic Game Boy Advance game such as Sonic Advance). Other changes can be found in the Chao Kindergarten. The Fortune-Telling House presents a fortuneteller that will suggest a name for your Chao. You can keep the name, try to get a better name, or select your own name. The Black Market is also a new addition. You can spend the rings that you have collected to buy things for your Chao, such as fruit. Finally, the last addition is Chao Karate. Chao fight each other until one of the Chao falls off the mat or cries. The success of the Chao depends on its stamina and strength.
Sonic Adventure 2 Battle is a great way to introduce GameCube users to the world of Sonic and fans of the Dreamcast can play an improved version of the original game.