While at the Gameplay Menu in the Options Menu, hold D-Pad Left + Left Analog Stick Right and press Start.  This will unlock the Codes Options at the Options Menu.

Unlock the Sega Sports, Visual Concepts, and Team 2K2

Type in MEGASTARS as a code.

Duotone Graphics

Type in DUOTONE as a code.

Trash in the Streets

Type in SPRINGER as a code.