you should be around level 8-9
Fight Wally who is by the door
At lavaridge town!!!!
Get four badges from other gyms.
Never because match call doesn't exist in sapphire.
It is the balance badge where you fight Norman(your father) in Petalburg City .
Beat then one at the time
from the fight area to the survival area and you may also migrate from ruby sapphire emerald migrate is to put Pokemon ruby sapphire emerald instead of the cover but you must put 6 Pokemon in the PC in ruby sapphire emerald then select in Pokemon platinum migrate from ruby or sapphire or emelard
after beating the elite 4 go find it
To up your Pokemon's to 100lv you have to fight the elite 4 100 time ......
Make all your Pokemon past level 57. You will definitely beat him or her then. Good luck!
If if its a lower level like 10-20 you should probably go to the cave on the mountain where you fight team aqua.
At Mt. Pyre, after you fight Team Magma, the old lady should go up to you and say that one of the members dropped something and she will give it to you.