Pokémon Red and Blue/Route 16-18

'Also known as "Cycling Road," Routes #16, #17 and #18 are a favorite hangout for bicyclists and motorcyclists alike. It just so happens that many of these two-wheeling enthusiasts are Pokémon trainers as well, and you must fight your way down the long slope to Fuchsia City. Once there, you will have a chance to visit the Safari Zone.'

Before you head past the guard post, dig your Cut-trained Pokémon out of the computer in Celadon City and use him to snip away at the tree blocking the northern part of Route #16. It's here that you'll find the patch of wild grass that is your first chance to catch a, as well as a secret house containing HM 02, Fly. Use this to teleport to any city you've visited, or for a two-turn Flying-type attack that is similar to Dig.

Route #17's brutal slope drags you downward unless you hold the or  buttons to steady yourself. But there's no reason not to speed to the bottom, since the only thing of interest here is the in Yellow. Although there are some pretty useful hidden items -- five in total -- if you're willing to stick around and fiddle with the Itemfinder for a while:
 * Rare Candy - In the center of the patch of grass
 * Full Restore - On the center bridge segment, a bit below its north entrance
 * Max Revive - South of the point where the west and center bridge segments connect
 * PP Up - On the east bridge segment, about halfway down
 * Max Elixer - South of the water at the point where the west and east bridge segments connect

When you get to Route #18, don't miss the trader in the top floor of the guard post.

Almost to Fuchsia City
Just before you arrive at Fuchsia City via Route #18, you will find three Bird Keepers waiting for you on the other side of the guard house. With the help of one little Electric Pokémon (you know the one), you can make short work of all three in no time.