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. 

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). 

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. 

Special Evolution bonus
Enter evolution mode. Then get the menu and select a Pokemon that has a star. Go through the entire evolution process. After the Pokemon evolves, a special evolution bonus worth 10,000,000 will be awarded. 

Double Cave bonus
Light up the letters C, A, V, and E to unlock the Cave bonus, but do not enter. Light up the same letters again, then enter the Cave to collect double the amount of points. 

Easy 10 million point bonus
Upgrade your Pokeball all the way to a Masterball by turning on all the lights on the top half of a board. Then, try to upgrade it one more time. This is much easier than having to evolve a Pokemon with a star next to its name. 

Easy Pokemon capture
Hit a Voltorb or Shellder, then hold A or B when their shadows appear. 

Findind rare Pokemon
On the third ball, light up all the "GET" lights and enter the hole. This will increase  the chance that rare Pokemon will appear. 

Finding Pokemon
Each Pokemon has a particular location where they like to hide: 

Red field
Pallet Town: Charmander, Rattata, Nidoran (M), and Poliwag 
Viridan Forest: Weedle, Pidgey, and Pikachu 
Pewter City: Spearow, Jigglypuff, Ekans, and Magikarp 
Cerulean City: Oddish, Mankey, Jynx, and Abra 
Vermilion City Seaside: Shellder, Krabby, Ekans, and Farfetch'd 
Rock Mountain: Voltorbe, Diglett, and MrMime 
Lavender Town: Gastly, Magnemite, Cubone, Electabuzz, and Zapdos 
Cycling Road: Spearow, Doduo, Lickitung, and Snorlax 
Safari Zone: Paras, Rhyhorn, and Chansey 
Seafoam Islands: Horsea, Staryu, Seel, and Articuno 
Cinnabar Island: Ponyta, Growlithe, Omanyte, and Kabuto 
Indigo Plateau: Machop, Onix, and Ditto 

Blue field
Viridan City: Squirtle, Nidoran (M), and Bulbasaur 
Viridian Forest: Caterpie, Rattata, and Pikachu 
Mt Moon: Zubat, Paras, and Clefairy 
Cerulean City: Bellsprout, Meowth, Jynx, and Abra 
Vermilion City Streets: Shellder, Krabby, Farfetch'd, and Sandshrew 
Rock Mountain: Diglet, Voltorbe, and MrMime 
Celadon City: Mankey, Meowth, Eevee, and Porygon 
Fuchsia City: Magikarp, Goldeen, Kangashan, and Exeggcute 
Safari Zone: Doduo, Nidoran (F), and Chansey 
Saffron City: Ekans, Sandshrew, Hitmonchan, and Hitmonlee 
Cinnabar Island: Ponyta, Koffing, Aerodactyl, and Magmar 
Indingo Plateau: Geodude, Ditto, Moltres, and Mewtwo.