Easy you go see steven to get the HM Dive then use it to go to Sootopolis City where your last gym is.
the seventh gym in pokemon sapphire is in mossdeep city.
In Pokemon Sapphire, Ruby and Emerald the 7th Gym that's located in Mossdeep City has Psychic type Pokemon.
go on google
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.
Go on to defeat the seventh gym in Mossdeep City, if you did not already catch Kyogre.
get a level 60-80 exploud that did the trick for me.
sootopolis city, after u awake rayquaza. the gym leader is juan, changed from ruby/Sapphire Wallace
the seventh gym is at sekka city
Easy you go see steven (he is in mossdeep city) to get the HM Dive then use it to go to Sootopolis City where your last gym is.
You have to surf from Lilycove to Mossdeep city so you can challenge the 7th Gym Leader, The psychic twins, Tate and Liza.
it is a dragon type Pokemon gym
Easy you go see steven (he is in mossdeep city) to get the HM Dive then use it to go to Sootopolis City where your last gym is.