normal Pokemon are bad against fighting type get fighting
with fighting type pokemon
go to your father and fight him to get the fifth badge
The sixth gem is with Leader Winona in Fortree city. You need surf to get to that city. You get surf from Wally's dad after you beat the fifth gym. You surf there from Mauville.
You go to Mauville city and go west, then go to the beach there and surf.
its in petalburg city.
Defeat all of the Gym leaders on Emerald. ~KKMG1
Go in. Beat the GYM. THAT SIMPLE
after you beat your father's gym
beat the 8th gym
Go back to your dads gym in petalburg
You get it when you battle your dad which is the fifth gym
Beat the gym leaders of:RustbroDewfordMauvilleLavaridgeThen return to petalburg and Norman will accept your challenge