Cycling Road is a big area with lots of trainers. The first couple of trainers are on bikes. They usually use poison pokemon so put your Kadabra/Hypno in front. After those trainers, the road should now be downhill. If you let go of the control pad, you will keep on riding downwards until you reach the bottom of Cycling Road. On the right is a patch of grass, but don't capture any pokemon there. Finally, you reach the bottom. Go right into the building. And come out of the building. You are now in Fuchsia City.