Well first off, you meet two trainers on the way to the first gym, and here are what they have:

Trainer Jish: Lv 6 Surskit
Lv 6 Kricketot

Trainer Jared: Lv 9 Voltorb


Here are the pokemon you can catch along the way:

Bronzor 15%
Rattata 15%
Electrike 15%
Kricketot 10%
Nincada 10%
Bidoof 10%
Magnemite 5%
Gastly 5%
Ekans 5%
Trapinch 5%
Seviper 2.5%
Spearow 2.5%
Voltorb 2.5%
Surskit 2.5%