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.
Chat with our AI personalities
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
i'm pretty sure you get it from Koga when you beat him(Koga is the 6th gym leader)
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.
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.
Answer: No you don't gain experience points, when you are battling with your friends ds, the only time you are going to get experience points in the Pokemon series is battling wild Pokemon and battling against trainers, gym leaders etc.