you cant theres only 16. last leader is Blue
Go to the forth gym!
go to the radio tower in Goldenrod city, team rocket will be there and you have to defeat them.
It is attainable in poke mart after the 3 gym badge (i think)
In one of the gyms. I don't know witch one.
dragon denyou can find dratini by surfing in dragon's den in blackthorn city. (the city where you get the eighth gym badge)
KANTO
You can't get a HM for that.
beat falker with a senret lv100
by beating the gym leader
Go to the forth gym!
You can find it at the town team rocket is defending
cinbar islnd
you have to get the cianwood gym badge and the olivine gym badge
In Mahogany town right from Etrack city
it is bugsy the bug type leader
by beating the icicle gym leader. In mahogany town.
blackthorn city