A recent edition of Famitsu has previewed the upcoming Wii version of Mario Baseball.
A translation via GoNintendo reveals the game has been built up on a new engine, instead of running off the previous GameCube version. There's a detailed story mode, seeing Mario and chums going at it again, spanning 9 unique arenas with unique gimmicks. For example in Yoshi Park, a Yoshi Train drives through the out field, Chomp Desert sees giant Chain Chomps litter the out field and in Smooth Ground Stadium the ground is far more slippery than usual.
Character wise, we've got special pitch and batting abilities, with Mario using his fireball tactics, Yoshi having an egg rainbow move and Bowser Jr. sending splodges of paint wherever the ball roams