it is bugsy the bug type leader
Go to the forth gym!
you have to get the cianwood gym badge and the olivine gym badge
blackthorn city
It is your rival from Pokemon fire red and leaf green versions.
in Goldenrod city
first get a ice type Pokemon then go threw the whole gym face gym leader and get the badge
It is in Ecrutuk city the leader is morty who uses ghost type Pokemon
It is attainable in poke mart after the 3 gym badge (i think)
You must go and battle Misty. Once you defeat her, she will give you a badge. You have then defeated the gym.
you go to azalea town
If you are playing heartgold or soulsilver , you need a physic or ground type pokemon.
Go to Saffron City and enter the gym and find a way to get to Sabrina