try loudred and breloom teach loudred rock smash and have it learn super sonic at level 23
battle them
To defeat or "beat" the 7th gym leader in Pokemon sapphire there twins and they have a solrock and a lunatone to beat them I suggest about level 40-50 water types.
The gym leader in the normal gym, your character's father will give it to you after you beat him.
go back to your fathers gym and defeat him
You need to beat the leader Norman (Your father in the game), the 5th gym leader.
Swampert.
The first 4 gyms are Rustboro City Gym leader Roxanne, Dewford Town Gym leader Brawly, Maulville City Gym leader Watson and Lavaridge Town Gym Leader.
im not sure which but u hav to beat a gym leader
beat the second gym leader. hope this helped! : )
go to fortree city and battle winona
You go to fight your dad as the 5th gym leader in Petalburg city. This happens after you beat the first 4 gym leaders.
go to the desert get the fossil and then go to petalburg city and defeat the gym there