You can only come from the top down through dark cave, so you cannot go up from route 2 even if you have flash
In Dark Cave.
You can find it in the Dark Cave.
Geodude, Dunsparce, Zubat and some water pokemon.
Route 31, outside of violet city.
In Gold and Silver Wobbuffet can be found in Dark Cave. In Crystal, in addition to Dark Cave, you can also get one at the Goldenrod Game Corner for 1500 coins.
Wobbuffet can be found at Dark Cave, which is at the entrance of Route 45.
hard stone can be found at dark cave
You have to go to the top of Bellsprout Tower and defeat the elder, in which you will get the item Flash. This move allows you to light up any dark cave.
A Dark Ball could work nicely here, since you're in a cave.
un cave of azela
You can't get Dark Lugia in Pokemon Silver, Gold, or Crystal. You can get Dark Lugia in Pokemon XD though. For Pokemon Silver, Gold, and Crystal it is just the regular Lugia.
It's Heart Gold btw and go to CherryGrove City and go North Till Dark Cave then West to Violet City hope this helps