look for steven on the east. talk to him. battle kecleon. he will give you a "Devon scope". go to the sixth gym. use Devon scope on the invisible barrier. it is a kecleon but it will flee. then you are accessible to the sixth gym.good luck getting the sixth badge. (tip: bring electric Pokemon along.)
Go to aquas base in Lilycove
with electric and fire type Pokemon
Go beat the 6th gym leader ^^, that is in Fortree City.
It depends which ones are you looking for. The 8th Badge is in Sootopolis, The 7th badge is in Mossdeep, The 6th Badge is in Fortree, The 5th badge Is your dad in emerald it is found at Petalburg, the 4th Badge is in Fallabore, The 3rd badge is in Mauville, The 2nd badge is in Dewford, The 1st badge is in Rustboro.
at the gym
Go to the Pokemon league.
the ground gym
Dewford Town.
Destroys picachew
You can get the 6th badge by defeating your father in petalburg.
you travel to lavavine town
Pokemon league