Talk to the girl in Celedon City that's always thirsty about 100-200 times. She will say your annoying and she will ask you to be quiet, say Yes and she will give you a Togepi.
After catching Mewtwo in the unknown dungeon, look around and fight a lot of Pokemon and you will run into mew.
Teach Snorlax surf and surf up & down on the east part of Cinnabar Island(half land half water) 20 times. Go to the Safari Zone and the first Pokemon you see is Dipogathie. Catch him and then fight another Pokemon, it will be Pikablu.
Use the item finder in front of Bills house. You'll find a bottle in the river with a note in it. It say's something about Pikablu.
Talk to one of the guards surrounding Saffron City 1000 times and he will give you Doomsay, Bruno, and Dofunyan. Then he will tell you that they are sympathy presents because your mother died. Go back to pallet and your mother will be on the ground. There will be a pokemon next to her called Pikaish. Fight Pikaish and if you catch it, your mother will be alive. If you don't then you can fight the ghost of your mother. Then, on the table will be Mewtwo's sister, Mewsta and a new updated Pokedex.
Go to Bill's house with these pokemon in this order. Dratini,Dragonair,Dragonite,Articuno,Zapdos,Moltres, and he will let you into his garden.
Go to Bill's house with Eevee, Flareon, Jolteon, Vaporeon, Mew, and Mewtwo and he will give you Togepi and let you into his cave and his garden.
Rematch at Brocks gym After you fight Brock, complete everything up untill you beat Misty in her gym. go back to Brocks gym(trade with a friend who has fly and fly back to Pewter city) and talk to brock and he will want to fight again. After you beat him he will give you a Pokemon that you don't have. Repeat this untill you have all of the Pokemon.
Secret city Beat the Elite 4 30 times and Prof. Oak will say that he's getting tired of all this and he will bring to a Secret city where you can trade Pidgeys for Mew.