• built on a brand-new engine
  • detailed story mode
  • 9 stadiums (not clear if there are more to be unlocked)
  • 4 players (2 vs. 2 / 1 vs. 2 or 1 vs. 3)
  • offensive items (attack outfielders with bombs, ect.)
  • day/night games
  • team stunts in the outfield (Mario jumps on Luigi’s head to catch higher-flying hits)
  • Wiimote swing for hits (based on timing/power)
  • swing Wiimote to pitch, twist to throw a curve
  • Every character has special pitching & batting abilities: Mario throws / hits a massive Fireball, Luigi uses the Tornado Ball, Yoshi has an Egg Rainbow move & Bowser Jr. sends splatters of paint everywhere which hide where the ball is.
  • shake Wiimote to run faster, but not necessary
  • Mario Stadium : Basic stadium with nothing added
  • Wario Fare : (extra features not mentioned)
  • Yoshi Park : A Yoshi Train drives through the out field. Hit the Baseball into Warp Pipes as well.
  • Smooth Ground Stadium : Ground is slippery / Giant Mr. Freezies are in the out field.
  • Chomp Desert : Giant Chain Chomps nip at players in the out field.

Information taken from latest Famitsu scans.