In Road To The Show mode, adjust all the sliders in your favor. Your player will do very well and get promoted faster.
Big baseball
Press Start to pause game play, the press Right, Down, Up, Left, Right, Left, Down, Up.
Big heads
Press Start to pause game play, the press Right, Left, Down, Up, Left, Up, Down, Left.
Classic free agents
Press Left, Right, Up, Left, Right, Up, Right, Down at the main menu to unlock classic free agents at the "Player Movement" menu.
Easy wins
When trailing (or winning) and you hit a ball into the ground or fly out, pause game play. Enter the "Controller Select" screen then choose the other team. Make them throw the ball to the wrong base or miss the fly ball.
Pitcher confidence
If you get pitchers from any other team, their confidence will rise much faster allowing you to strike out more batters and walk less. They must have at least two or three "A"s in their ranking.
Sliver Era and Golden Era teams
Press Right, Up, Right, Down, Down, Left, Up, Down at the main menu.
Small heads
Press Start to pause game play, the press Left, Right, Down, Up, Right, Left ,Down, Left.