Pong
Level select
At the options screen, press L1, R1, L1, R1, L1, R1.

Unlock first level in all zones
At the zone selection screen, pause the game and press
L1, R1, L1, R1, then resume the game.
Unlock second level in all zones
At the zone selection screen, pause the game and press
L2, R2, L2, R2, then resume the game.
Unlock third level in all zones and more
At the zone selection screen, pause the game and hold
L1 + R1 + L2 + R2, then resume the game.
Game Shark Codes
P1 Score Modifier 801F2B8C 00??
P2 Score Modifier 801F2CFC 00??
Have All Gold Bars 801F1C84 0063
All Power-Ups P1
(GS 2.2 or Higher Needed) 50000E02 0001
                          301F5020 0001
Golden Atari Sign 801F1E90 0015
                  801F1E94 0015
                  801F1E98 0015
Unlock Zone 2 801F1CD0 0100
Unlock Zone 3 801F1D10 0100
Unlock Zone 4 801F1D50 0100
Unlock Zone 5 801F1D90 0100
Unlock Zone 6 801F1DD0 0100
Unlock Zone 7 801F1E10 0100
Unlock Zone 8/Old School Pong 801F1E50 0100
Unlock All Penguin Pong Levels 801F1C94 0105
                               801F1C96 0101
Unlock All Soccer Stars Levels 801F1CA0 0105
                               801F1CA2 0101
Unlock All Log Jam Level 801F1CAC 0105
                         801F1CAE 0101
Unlock All Clown Around Levels 801F1CB8 0105
                               801F1CBA 0101
Unlock All Beach Party Levels 801F1CD4 0105
                              801F1CD6 0101
Unlock All Rock N Roll Levels 801F1CE0 0105
                              801F1CE2 0101
Unlock All Seal Jungle Levels 801F1CEC 0101
                              801F1CEE 0101
Unlock All In A Spin Levels 801F1D14 0105
                            801F1D16 0101
Unlock All Puck Pong Levels 801F1D20 0105
                            801F1D22 0101
Unlock All Fishing
Frenzy Levels 801F1D2C 0101
              801F1D2E 0101
Unlock All Jungle
Japes Levels 801F1D54 0105
             801F1D56 0101
Unlock All Balloon
Circus Levels 801F1D60 0101
              801F1D62 0101
Unlock All Flock
Fiasco Levels 801F1D6C 0101
              801F1D6E 0101
Unlock All Dervish
Danger Levels 801F1D94 0501
              801F1D96 0101
Unlock All Pongball
Wizard Levels 801F1DA0 0101
              801F1DA2 0101
Unlock All Frog
Follies Levels 801F1DAC 0101
               801F1DAE 0101
Unlock All Henhouse
Surprise Levels 801F1DD4 0501
                801F1DD6 0101
Unlock All Polar
Pivot Levels 801F1DE0 0101
             801F1DE2 0101
Unlock All Zone
7 Levels      801F1E14 0101
              801F1E16 0101
Unlock Pong
Size/Speed Secret 801F1EA2 0001
                  801F1EA6 0001
                  801F1EDE FFFF
Have Ball Speed
Secret 801F1EAA 0001
       801F1EE0 FFFF
Have Grab Secret          801F1EAE 0001
                          801F1EE4 FFFF
Have Whack Secret         801F1EB2 0001
                          801F1EE8 FFFF
Have Spin Grab Secret     801F1EB6 0001
                          801F1EEC FFFF
Have After Touch Secret   801F1EB8 0001
                          801F1EF0 FFFF
Have Smart Bomb Secret    801F1EBC 0001
                          801F1EF4 FFFF
Have Magnetic Grab Secret 801F1EC0 0001
                          801F1EF8 FFFF
Have Boomerang Secret   801F1EC4 0001
                        801F1EFC FFFF
Have Stretch Secret     801F1EC8 0001
                        801F1F00 FFFF
Have Spike Secret       0801F1ECC 0001
                        801F1F04 FFFF
Have Turbo Throw Secret 801F1ED0 0001
                        801F1F08 FFFF