Route 5
Description Of Route 5:
After you have defeated the Cerulean Gym, visited Bill, and have shopped Team Rocket, next only accessible route is to the south of the city. Route 5 doesn't have much in it outside a few Wild Pokemon and the Pokemon Daycare, and since you yet don't have access to Saffron City, you have to take the Underground Path to Route 6.
The only significant thing on this Route / Underground is the next Pokemon Trade. This person can be found right as you enter the building on the underground path, but, unfortunately, it is just for a Nidoran Female. It really isn't necessary to trade with this person.
Pokemon In Route 5:
Grasses:
Bellsprout - Levels 13-16 - 40% Appearance Rate
Pidgey - Levels 13-16 - 35% Appearance Rate
Meowth - Levels 10-16 - 25% Appearance Rate