To improve your players' skills, press A, A, A, A, B, B, B, A, B, A, B, A, B + Select at the Today's Match-up screen or the Tonight's Match-up screen.
Bonus Players
At the title screen, press B, B, A, A, B, B, A, B, A, B, B, A, B, Select, B, Select, A, Select.
Bonus Teams
At the title screen, press A, A, B, A, B, A, B, B, A, B, A, Select.
Display Shot Percentage
At the Tonight's Match-up screen press Down, B, Up, Up, Down.
Improved Three-Pointers
At the Today's Match-up screen, press B, B, A, A, B, A, B, B, A, B, A, A.
Max Team Points
At the main menu, go to Game Options then Edit Team. At the Edit Stats screen, hover the cursor next to "Exit" and press B, A, Down, Right, A, Down, Up, A, Down. This will max out the point values for all members of the current team (setting them at 60).
Better Skills...