talk to Archie in mt.pyre then you will be able to enter.
you will go to lavaridge town again from cablecar and then go to south the ground will shake and there will be a hole and you will enter the magma hideout
First start from sootopolis and dive on the dark water. Get out of the cave. Dive up and you will appear on the sea. Surf east the you will see a small diving place. tgis ia not the destination! Continue west then you will sea a thick diving area. Dive. Go around until you see a cave. Enter it. If there is a submarine, that is the hideout. Use dive to dive up and there you are. The hideout!
First you need to go to mt pyre and beat every grunt there and talk to the elderly. then go to the vulcano neart to lavaridge town and jump down the hills. Then a cave will appear. after you defeat maxie in that cave you can enter team aqua's hideout.
with an action replay or gameshark
You walk in.
You cannot get the codebreaker on Pokemon emerald you have to buy it its a thing you can plug into your GBA (GameBoy Advance) and enter in a code and there you go.
In Emerald, an old lady in Mt. Pyre will give you Magma Emblem. After you got it, go to Judged Pass. If you bring the Magma Emblem, the Magma Hideout will appear in Judged Pass.
to enter the elite four
You press enter-enter means start. Backspace is select.
well... to know the cheat in Pokemon emerald just watch a you tube just type this, how to cheat in Pokemon emerald..now just enter ..ok
It is Altering Cave which you can enter only after you beat the Pokemon league.
beat team rocket's hideout in celadon city, defeat erika and enter silph co. :) hope i helped