How can i get Dratini on Pokemon Crystal?

Go to Dragons den above Blackthron city. Go in and surf down next to the guy in red. Keep going until your reach a bit of land. Land on there take your super rod out fish there you will find a level 40 dratini or a level 40 dragonair they come quite often so id say wait for the dragonair. Level it up 15 levels and you got a dragonite.