No one, there are only 9 gym leaders
After beating Blue you go to Professor Oak's lab in Pallet Town.
From Pallet town travel down until you find water heading downwoods. Enter cinnabar islands and head east. enter a cave and go up the ladder. Vs gym leader 7. After you defeat him go to cinnabar island and talk to blue. Blue gos back to the gym where you can vs him.
in the begging of the game theres a gym near pallet town that's where Giovanni is the last gym leader
sootopolis city
The last gym leader gives it to you
Depends what game version you're referring to. I don't know much about any game BEFORE Generation 4, except Emerald. But I do know that in Heart Gold/Soul Silver, Blue, is on the Island where Blaine's Gym USED to be. Once you have the other 7 Kanto badges (Excluding the Viridian City one), go to Cinnabar Island (South of Pallet town), and Blue should be there. Talk to him, he will go to his Gym.
the last gym leader is Blue.When you go to the seventh gym leader Blaine you should see Blue and asks you if you have 7 badges then you beat Blaine and go to Blue and he says to meet him at his gym
The last gym leader has one
Blue, the last gym leader in kanto region
blue in viridian city
You use the key to get in o the fire gym to get into the last gym.viridian city which is above pallet town which is where you began.Viridian City.The leader is Giovanni, who uses Ground-types.
The last gym leader Blue is first at cinnibar island talk to him so that he returns to his gym go to viridian city and go into the gym battle Blue to receive the last badge.