His name is Blue. He's in Virdian City in Kanto. However, You can only battle him when you have all the other gym badges in Johto and Kanto (Note: Blaine is found in the Seafoam Islands, when you visit Cinnabar you'll see why) and talked to him on Cinnabar Island.
you beat the last gym leader in johnto
get stronger then you are before
you have to beat the last gym leader
after you defeat trainer blue, the last gym leader in kanto, talk to prof. oak. he will give it to you
you must frist go to seafoam island where blaine is, he is the 15th gym leader, then go to cinnibar island and a character who is behind the Pokemon center will then say that he is the last gym leader, once you have talked to him he will go to viridian city gym, he is the last gym leader. this is for heartgold and soulsilver :) hope this helped.
You find him in the last Gym in Sootoolis City.He is the last Gym leader
In her Gym
He's called Green and he's the gym Leader of the last Gym. Beat all the other gyms then beat him.
well,i only know what to do in soulsilver but its probably the same. you have to go on the teleport/forwardy things in the gym until you get to the gym leader i hope this helps
Well the last gym leader is a dragon type leader so you need an ice type pokemon and/or dragon type pokemon. Idk what his name is but a guy gives you a level 15 Datrini and it is a dragon type pokemon. For an ice type pokemon, go back to the cave (idk the name of the cave but it is a ice cave) and get an ice type pokemon like swinub and raise him and beat Blair!
in the grass in the last city the 8th gym leader
GET THE LAST BADGE......