Ecco The Dolphin - Cheat mode:
By turning Ecco to the left or right. Pause your game when Ecco is facing the screen. Push Right, B, R, B, R, Down, R, Up. A cheat menu with stage selection, sound select, and unlimited life will appear.

Golden Axe - Level select:
After picking arcade mode. Press and hold Down/Left + B and press Start at the character selection screen. A number that corresponds to the starting level will appear in the upper left corner of the screen. Use the D-pad to change this value.

Golden Axe - Nine continues:
Pick arcade mode. Press and hold Down/Left + A + R. Release the buttons and press Start.

Sonic Spinball - Level select:
Press A, Down, B, Down, R, Down, A, B, Up, A, R, Up, B, R, Up at the options screen. Enter one of the following controller actions to start at the corresponding level.

Level 2 (Lava Powerhouse)
Press and hold A and press Start.

Level 3 (The Machine)
Press and hold B and press Start.

Level 4 (Showdown)
Press and hold R and press Start.

Sonic Spinball - Multi-ball stage:
Get all the rings on a level and use the gate that appears to be a large shining ring.