Go east from cerulean city keep going until you reach water go south and into the cave this is Rock Tunnel.
rock tunnel
Get to Lavender Town through Rock Tunnel (or Fly there, but the HM is impossible to get until you have already visited Lavender Town.)
After getting HM1 CUT go east of cerulean city and cut down the tree, continue east and eventually find a cave that is rock tunnel.
The rock tunnel can be found by the power plant (east of Cerulean City. You have to cut a tree to get to the path and then follow the path and you will find the entrance to the rock tunnel right next to a Pokemon Center). The rock tunnel leads to Lavender Town.
you have to get it from a special event
rock tunnel
You take rock tunnel..........
Rock Slide is taught by a move tutor in Rock Tunnel.
Rock Tunnel is located due east of Cerulean City, around the corner from the pokecenter.
head west of cerulean city to the Rock Tunnel
in power plant, near entrance to rock tunnel, have to surf to it
use the move Flash (TM70)
i caught mine on the path from Cerulean city to Rock Tunnel
you can find zapdos in the power plant just below the rock tunnel
It is east of cerulean city, HM1 CUT is needed and HM5 Flash.
Onix can be found on seven island, six island and rock tunnel.
Go to Rock Tunnel at Cerulean City(maybe I spelled it wrong) there would be a boy in there with the yellow hat will teach one of your Pokemon(you have to have a Pokemon that is a rock type)