Faster ball upgrade:
When the Pokeball hits the first three lights at the top, press Left to move the light. It can also be moved by pressing A.

Moving Pokemon in Pokedex:
Select an unevolved or basic Pokemon, then press Start to watch it move in the Pokedex. Note: This trick only works when the game is played in a Game Boy Color system.

Pokedex record:
Enter the Pokedex and press Select to view how many Pokemon have been obtained and seen.

Bonus levels:
Bonus levels are unlocked by capturing three Pokemon in the same location without getting a "Game Over" screen or changing to a different location before returning. If this is accomplished a hole marked "Go To Bonus" will appear. Enter the hole to reach the bonus level. The Red pinball machine has a Diglett's Cave bonus level, and the and blue pinball machine has a Meowth's House bonus level.

Mew:
Mew is a bonus character that is worth a lot of points. In red, go to the Digglett, Gengar, and Mewtwo stages twice. In blue, go to Meowth, Seel, Mewtwo stages twice. Go to Indigo Plateau in map mode. Then go into a get mode to have a 6% chance of Mew appearing. Hit Mew with the Pokeball for the bonus points. Note: This trick requires a Game Shark cartridge. Enter 919679D5 as a GameShark code and leave the GameShark cartridge off. Start a game and get into a catch 'em mode. Proceed to catch the Pokemon, and when the four "Catch!" lights are lit, get ready to turn on the GameShark. Hit the Pokemon again, and as soon as the ball hits, turn on the Gameshark. A message stating that Mew was caught will appear at the bottom of the screen. Save the game and check the Pokedex. Mew should be there. Return to the game and try to evolve Mew. It does not matter if you are successful, but your Pokedex will return to normal. If you do not, when you press Select to see how many Pokemon have been caught, 151/150 will appear (if you have all other Pokemon).

Hints:
Secret Mewtwo bonus stage Complete both bonus stages in the machine that you are playing. In red field, clear the Digglett and Gengar stages. In blue field, clear Meowth and Seel stages. Then when you catch three more Pokemon or get a chance for another slot, you can reach the Secret Mewtwo bonus stage. Once in the stage, hit Mewtwo as much as possible. If he is hit enough times, he will stop creating the balls. When this happens, you can hit him three more times to clear the stage. However, do not do this, since it will start the cycle over again. By leaving the Mewtwo stage uncleared, you may keep returning to it and get higher scores.

Evolve Pokemon in the red field:
Shoot the Pokeball through the left outside loop. Each time it passes through the loop, one evolution arrow will light. When all three arrows are lit, shoot the ball into the Evolution cave. Then, choose the Pokemon to be evolved.

Evolve Pokemon in the blue field:
Shoot the Pokeball through the left loop. Each time the Pokeball passes through the loop, one evolution arrow will light. When all three arrows are lit, shoot your ball into Slowpoke's mouth. Then, choose the Pokemon to be evolved.

Easier way to evolve Pokemon:
After entering evolution mode, quickly hit the buttons with the flashing arrows next to them. Do not try to raise Pikachu's lightning meter. The "Ball Saver" will stay lit for awhile. During this time, after hitting a button with a flashing arrow, allow the ball to move below the flippers. After the ball is launched, if the item you are looking for is near the top, you will have a good chance of getting it.

Note: If this is attempted, always make sure that the "Ball Saver" is not going to run out.