Famitsu shed some light on the details of Final Fantasy X-2 International's Last Mission. It mentioned how the mission would last 20 hours long, consist of 80 floors, have a new battle system, and be the closing chapter of the Final Fantasy X series. It was also mentioned that there would be a new dress sphere hidden somewhere in the dungeon (in which the last mission takes place). In addition, the new battle system will have a ticker at the bottom of the screen which describes events happening in battle. For example, it could say "Yuna reached Lvl 33". The ticker seems very similar to what you would find in blitzball. Finally, the article (scan) discussed how there would be new items and abilities in the game aswell.

Link >> Famitsu Magazine Scan

The magazine scan shows images of the new battle system, and the ticker mentioned in the article above.