Excerpt from [wikipedia]:
“On January 6, 2011, it was revealed that Dead or Alive: Dimensions will incorporate a “Chronicle Mode” feature, which acts as a story mode in the game. In Chronicle Mode, which goes through all four Dead or Alive tournaments, the player will assume the roles of various fighters from the series. It was also said that the 3DS’s touch screen will be used for executing special fighting moves for his or her character, while the top screen would be used for displaying the fight. Dimensions will also use the 3DS’ StreetPass feature to make AI representations of the player, based on their play patterns, challenge other owners of the game.
The other modes featured are “Arcade,” in which the player fights for additional time; “Survival,” in which the player fights until he defeats all opponents or is knocked out; “Free Play”; “Training”; “Showcase,” in which the player position 3D models on a stage and takes 3D photos of them; and “3D Photo Album,” in which the player views the photos taken in “Showcase” mode.”