He is the fuchsia city gym leader.
Because he doesn't.
Look at the map after you beat Koga...
In Pokemon Red, the fifth badge is possessed by the Poison-Type Koga. The badge is named Soul Badge. It lets you use Surf outside of Battle.
The fifth gym leader Koga uses Poison type pokemon so your best bet is to use Psychic or Ground types against them. A Kadabra(Alakazam would be even better) can easily take care of all of Koga's pokemon.
you need to have all ground type Pokemon to beat koga i would say a a nidoking of nidoquenn you need to have all ground type Pokemon to beat koga i would say a a nidoking of nidoquenn
The poisonous gym of Koga's command in Fuchsia city comes first in Pokemon fire red and in Pokemon leaf green
i'm pretty sure you get it from Koga when you beat him(Koga is the 6th gym leader)
Koga uses primarily Poison-type Pokemon. Psychic Pokemon would be the best bet. Ground-type Pokemon would also work, but will not be as effective against his Venomoth or Crobat.
Same as regular red/blue: I believe it is listed as sabrina, but you can skip ahead and beat koga first
Koga's Pokemon are: Koffing Muk Koffing Weezing
From the leader Koga in Fuchsia City
Miltank Nicknamed: Milkshake Idiot no it isn't