In MLB 12 The Show’s diamond dynasty mode it is up to your to build a championship roster from a combination of Major League and customized players. You can customize your logo and uniform any way you want it. You can also edit any of your players and train them to become an all star. Dynasty cards range from bronze to platinum. They can include up to 5 tool bonuses like power, contact, speed, etc.
You will have to spend your budget wisely to train your team. Of course if you run out and don’t want to earn more the hard way, you can purchase extra credits through the PlayStation Store. There are too many cool new features to list here but the video below does a great job of explaning them.