Pokemon Soul Silver Help

[AnimalCrossingGurrl]

OK, right now I'm in Ecruteak City and I'm trying to battle the gym leader Morty... He uses ghost-type Pokemon.

So, what Pokemon type(s) should/can I use against ghost type Pokemon...?

Help.

 

[Fontana]

Ghost, Psychic, or Dark types.

 

[Vex L'Cour]

If you can, get a Giraffarig.