@GothamsBeard get a Taillow in Route 104. It must be a male. You can name him Jose. He must evolve by the 3rd gym.
@ShinyEspeon0249 get a Caterpie, name if male John, female Lulu, it may evolve freely into Metapod, but if you want Butterfree, it must beat the trainer in Brock's gym's Sandshrew. Also, get a Rattata, must be male and named Joey, he has to beat Misty's Starmie in order to evolve. If he doesn't, you must evolve him at the rival battle in the bridge against Pidgeotto.