Streets of Rage 2

Cheat mode:
Highlight the "Options" selection at the main menu, hold A + B on controller two, and press any button on controller one. Additional options that allow level selection, new difficulty levels (Mania and Very Easy), and increasing number of lives up to nine will be displayed.

Two players as same character:
Hold Down/Right + B on controller one and Left + A on controller two at the title screen. Press C on controller two while all buttons are held. Select two player mode and choose the same character. Note: Both characters will appear identical.

Two players as same character (European version):
Hold Right + B on controller one and Left + A on controller two at the title screen. Press C on controller two while all buttons are held. Select two player mode and choose the same character. Note: Both characters will appear identical.

Bonus life:
Move to the left corner of level one and press Punch.