Yellow Walkthrough

    When you first start the game, you'll be in your room. Exit the room and get out of the house. Then,  attempt to go up the road to Viridian City. You'll be stopped by Professor Oak. He'll lead you to his lab and will tell you to pick a Pokémon. That Pokémon is Eevee. But when you try to pick it, Gary will run forward and shove you away, claiming Eevee for himself. Professor Oak will see this and will give you the Pikachu he just caught. Then, Gary will challenge you to a battle. Beat him to get experience points. 

    Now, make your way to Viridian City (on the way, talk to the first guy you meet to get a Potion). When you get there, go into the Pokémart to get Professor Oak's parcel. Then, deliver it to him to receive your Pokédex and to make the man blocking the road move out of the way. After delivering, you should go back to Viridian City and either look for a road heading west (this is optional), or you can continue following the road heading north. (There is no point in going to the gym because it is closed.) The one heading west will take you to the Pokémon League entrance. The one heading north will take you to Viridian Forest, making you one step closer to Pewter City.

    Viridian Forest is full of tall grass and wild Pokémon. You'll have to be very careful when you navigate its many forks and turns. Some trainers are also lurking and will challenge you to battle if they see you. Make your way through by following the road east (right), north (up), west (left), south (down), west (left), north (up), west (left), south (down), west (left), then north (up) all the way to the exit. You'll still need to follow that road north a bit before you can see Pewter City.

    In Pewter City, you will encounter your first gym (ok, maybe your second). The leader is Brock, a rock/ground type specialist. Make sure that you train your Pokémon to at least level 14, before you try to battle. He has a level 12 Geodude and a level 14 Onix. When you beat him, he'll turn over a Boulder Badge.

    Now, go to Mt.Moon by following the road east (you can't get there until you've beaten Brock). Mt. Moon has many floors. Lots of trainers are waiting to battle, so you'd better train hard on wild Pokémon. Capture a few too, so you can add to your Pokémon collection. You'll also meet Team Rocket there, so that's another reason to train. If you beat them, you'll get to choose between 2 fossils, helix and dome,  used to clone Omanyte or Kabuto. Pick whichever one you want and move on.

    You'll come to Cerulean City now. Go up the bridge to find Bill's house. You'll meet your rival and five other Pokémon trainers on the way. Defeat them to get a Nugget (it's an useless item that's worth a lot of money). When you reach Bill's house, help him turn himself back to a human (he accidentally put Pokémon DNA in himself). You'll be rewarded with a S. S. Anne ship ticket.

    After you get the ticket, go back to Cerulean City and look for the gym. The gym leader is Misty. She specializes in water type Pokémon. Her Pokémon include a level 18 Staryu and a level 21 Starmie. If you chose a Charmander as your first Pokémon, your in big trouble. Otherwise, level up your Pokémon to level 22 and start battling. If you win, she'll give you a Cascade Badge.

    Now, go through the Underground Tunnel to reach Vermillion City because you can't get to Saffron. First, talk to the people until you find the Old Rod, used to fish for Pokémon. Then find the Bike Voucher, used to exchange for a bike in a bike shop back in Cerulean City. Now, use your S.S.Anne ticket to get on the ship. Find the captain's room. You'll meet your rival there at the entrance. Beat him and help the captain cure his seasickness. You'll be rewarded with HM 1, Cut. Use this technique to cut down the tree blocking the way to the gym.

    This gym is controlled by Lt. Surge. Lt. Surge will be in a room behind locked doors. However, you can open the doors by checking the trashcans littered on the gym floor. Some of the trashcans contain hidden switches. Find two of them to open the doors. When you find one, though, you'll have to find the second one next. Otherwise, the switches will reset and you'll have to look for them all over again. After you open the doors, you'll see Lt. Surge. He specializes in electric type Pokémon, including a level 21 Voltorb, a level 18 Pikachu, and a level 24 Raichu. When you beat him, he'll hand over his Thunder Badge.

    After you get the Thunder Badge, you should go through Diglett's Cave. Diglett's Cave is full of Digletts and some occasional Dugtrios. At the end, there will be a house. Inside, you'll find HM 5, Flash. Flash is used to light dark caves, so you can see.

    Now, go back to Cerulean City. Use Cut to get rid of the tree blocking a road. It will be lined with several Pokémon trainers. At the end is a cave called Rock Tunnel. When you first enter Rock Tunnel, you can't see anything. Use Flash to illuminate the area and to enable you to see. You'll have to see to get through. Otherwise, it is nearly impossible.

    Rock Tunnel has 2 floors. It is not very difficult to navigate, though. Just follow the path and after several ladders, you'll come to a final ladder with a sign near it. That ladder leads to the exit. 

    You'll end up in Lavender Town. Lavender Town doesn't have anything in particular, unless you count the Pokémon Tower. But you don't need to get through the Pokémon Tower yet. You just need to use Lavender Town's Underground Tunnel to go to Celadon City.

    In Celadon City, there is a place called Game Corner. There are some suspicious activities going on, so check it out. Look for the guy in a black suit standing in the back of Game Corner room. Talk to him. He'll challenge you to a battle. If you beat him, he'll leave. Check out the poster behind him. It'll review a secret switch. Press it to make a secret set of stairs appear. Go up the stairs. It seems like Team Rocket has taken over the building. Climb all the way to the top to meet Giovanni. He'll be guarded by some other Rockets. Defeat them to get to Giovanni. Giovanni will challenge you to a battle. He will have an Onix , a Rhyhorn, and a Kangaskhan. All of his Pokémon are between levels 25 and 27. Beat him to make him leave. He will leave behind the Silph Scope, used to see ghosts.

    When Giovanni has left, get out of the building and go to the gym. Erika is the leader. She specializes in grass type Pokémon. Some of her Pokémon include a level 29 Victreebel, a level 24 Tangela, and a level 29 Vileplume. After beating her, she'll give you a Rainbow Badge.

    Now, go back to Lavender Town. Team Rocket has now taken over Pokémon Tower and has also taken Mr. Fuji as a hostage. When you get there, Gary will be waiting for you. He'll challenge you to a battle.  He will have a level 25 Pidgeotto, a level 23 Gyarados, a level 22 Growlithe, a level 20 Kadabra and the Pokémon he chose in the  beginning. When you beat him, continue to climb up the floors. On the fifth floor, there will be a healing zone. Step on it to heal all of your Pokémon. On the last flight of stairs to the seventh floor, you'll encounter the ghost of a Marowak. Defeat the ghost Marowak to continue to the seventh floor. When you get to the seventh floor, you'll meet Team Rocket. Beat them all to rescue Mr. Fuji. Mr. Fuji will lead you back to his house and will give you a Poké Flute. A Poké Flute will wake up any sleeping Pokémon.

    Now, go back to Celadon City and buy a drink (any kind). Give it to the guard that's guarding Saffron City. After you give it to him, he'll let you through. Team Rocket has now taken over Silph Co. Stop them by going to the building's top floor. But first, you'll encounter Gary. Gary'll have a Pidgeot, an Alakazam, and a Growlithe. All of them will be between the levels 35 and 40. Afterwards, he'll leave and you'll be able to go on. On the highest floor, you'll meet Giovanni again. This time, he has taken the president of Silph Co. hostage.  Giovanni will have a Nidorino, a Rhyhorn, a Nidoqueen, and a Kangaskhan. Defeat him to free the president. He will give you a Master Ball, the best Pokéball in the game.

    After defeating Giovanni and saving Silph Co., you should head out of the building and go to the gym. There are 2 gyms, but the real one is controlled by Sabrina. Sabrina's specialty is psychic type Pokémon. She has a level 38 Kadabra, a level 37 Mr. Mime, a level 38 Venomoth, and a level 43 Alakazam. When you beat her, she'll give you the Marsh Badge.

    The other gym in Saffron City is actually a fighting dojo. If you beat the leader there, he'll reward you with either a Hitmonlee or a Hitmonchan (you pick). Both of them are very rare fighting Pokémon.

    Next, head down to Fushcia City by either Cycling Road or routes 12-15. Go to the Safari Zone and find the Gold Teeth. Continue on to find a secret area. There will be a house there. Go inside and talk to the person. He will give you HM 3, Surf. Surf allows you to swim in water. Now, exit Safari Zone and give the Gold Teeth to him. He will reward you with HM 4, Strength. Strength allows you to move boulders.

    After you get HM 4, go to the local gym. The gym leader is Koga, a poison type specialist. He has a level 37 Koffing, a level 39 Muk, another level 37 Koffing, and a level 43 Weezing. When you win, he'll reward you with a Soul Badge.

    Now, surf down to Seafoam Islands. Get through it by rolling boulders into holes on the floor. Do this for every boulder and hole you encounter to stop the current from sweeping you back toward floor 4. You can also fly back to Pallet Town and surf south to get to Cinnabar Island. 

    When you get to Cinnabar Island, the gym will be locked. Look for the key in the burned Pokémon Mansion. The burned mansion requires you to find hidden switches in statues. These switches switch open an lock certain doors. Use this technique to get the key.

    Take the key to the gym door. Inside, you'll encounter a series of rooms blocked by a door. Inside each room is a trainer. You can unlock the door by either beating the trainer or answering a question asked by the machine in the back of the room. If you answer correctly, the door will open. If you don't, the trainer will come and battle you. The leader of the gym is Blaine. He is a fire type specialist. His Pokémon are a level 42 Growlithe, a level 40 Ponyta, a level 42 Rapidash, and a level 47 Arcanine. If you win, he'll hand over a Volcano Badge.

    Now, fly to Viridian City. The gym leader (which is Giovanni)  will be back. He specializes in ground type Pokémon. Battle and defeat him to get your final badge, the Earth Badge. Now you're on your way to the Pokemon League!

    Go through the front gate on the west side Viridian City. Continue on until you come to a cave. That cave is Victory Road, the last obstacle to finding the Elite 4. Victory Road is full of powerful Pokémon. There are 3 floors in all. At the exit, you'll come to another road. It is a very short road. Follow it to the Pokémon League  Center. It is a place with a Pokémon Center and a Pokémart. In the back is the steps leading to the Elite 4.

    Now get ready for a very tough battle! The 1st of the Elite 4 is Lorelei. Her Pokémon are all ice types. They include a level 54 Dewgong, a level 53 Cloyster, a level 54 Slowbro, a level 56 Jynx, and a level 56 Lapras. You should use a fire, fighting , or rock type to pulverize her team.

    The next of the Elite 4 is Bruno. His special is fighting type. His arsenal includes a level 53 Onix, a level 55 Hitmonchan, a level 55 Hitmonlee, a level 56 Onix, and a level 58 Machamp. You can cut them down to size with a flying or psychic type.

    Agatha is the next Elite 4 member. Her specialty is ghost type Pokémon. It includes a level 56 Gengar, a level 56 Golbat, a level 55 Haunter, a level 58 Arbok, and a level 60 Gengar. You should use a psychic type, a ground type, or a fire type to beat them.

    The last member of the Elite 4 is Lance. He specializes in dragon types. His team has a level 58 Gyarados, a level 56 Dragonair, another level 56 Dragonair, a level 60 Aerodactyl, and a level 62 Dragonite. A high level ice or fighting type will do the trick.

    There will be a surprise when you beat all of the Elite 4 members. It seems that Gary has already beaten the Elite 4. You'll have to defeat him too to be the true Pokémon League champion. Gary's arsenal includes a level 61 Pidgeot, a level 59 Alakazam, a level 61 Rhydon, and the other 3 Pokémon will be depending on what you chose for your starting Pokémon. If you chose Charmander, his last 3 Pokémon will be a level 61 Cloyster, a level 63 Ninetales, and a level 65 Blastoise. If you chose Squirtle, his Pokémon will be a level 61 Gyarados, a level 63 Arcanine, and a level 65 Venusaur. If you chose Bulbasaur, his Pokémon will be a level 61 Exeggcute, a level 63 Gyarados, and a level 65 Charizard. After you beat Gary, you'll be declared the official Pokémon League champion. Professor Oak will take you to the champion's room and you'll get to see the credits.

    After you see the credits, the game will restart. Continue your game and fly to Cerulean City. You'll see that the person previously blocking the Unknown Dungeon would have disappeared. You can now enter it. Inside, you'll discover the most powerful Pokémon in the game. Deep in the dungeon will be Mewtwo. Mewtwo is the most powerful Pokémon in the game (besides Mew). If you saved your Master Ball, then you should definitely use it for Mewtwo. But if you didn't, then all I can say to you is, good luck! You'll need it!