You have to go back to petalburg city to battle your dad at the gym!
At lavaridge town.
Head to lavaridge town for your next badge.
In Lavaridge Town
you need the fire badge in lavenderige town kk good luck
in lavarage town
Use mr briney's ship to reach dewford town.
After beating Flannery, the Gym Leader of Lavaridge Town and receiving her Badge which makes it your fourth earned Badge, you will then need to make your way back to Petalburg City so that you can challenge your in-game Dad, Norman to a Gym Battle.
In Shingo town in the cave where you VS Rayquaza after the game (And Kyrogre)
Lavaridge town is where you get the fourth badge in ruby.Hint:the gym leader uses fire types so use a water type.
You can get the 6th badge by defeating your father in petalburg.
In the mountain next to the 4th Gym's town (forgot what name).
you use the hm surf that you recently got from defeating the 4th gym. surf eastward from Mauvile city