Information coming from the most recent Famitsu scan…
- 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.
Thanks to Josh for the heads up!