OK it took me two tries to get this but once you get to the room with 4 sets of teleporter's it really easy... once you get in the hideout go right then up and up the stairs, then go to the teleporter to the left. You will come to another room with water next to you and a telporter just over the other side of it below you just barely in the picture. Walk along the water all the way around to that teleporter that you just saw earlier and step in it. You'll come to a room with 3 teleporters in front of u , go in the right one, then the middle one, then the left one, then the far left one (NOT THE MIDDLE ONE!). The masterball is one of those four pokeballs in that next room. You cant use an escape rope to get out so just do all the steps in reverse to get out and then you have the masterball. Hope it helped... (use it on rayquaza, kyogre and groudon can be caught easier then rayquaza with regular pokeballs and ultra balls)
after getting into team magmas hideout
The Team Aqua boss is in the Team Aqua Hideout northeast of Lilycove City. You will need the HM move Surf to reach the hideout.
team magmas hideout is where you go down from the cable car, east of lavaridge. aqua is a surf north away from lilycove or mossdeep, i forgot sorry.
you battle them
You find it in the team aqua hideout.
you are supposed to beat team aqua to get into in team aqua's hideout you are supposed to beat team aqua to get into team aqua's hideout in lilycove city
battle all team aqua
after getting into team magmas hideout
You can find team aqua's hideout in the east side of Lilycove City in Pokémon Sapphire.
The Team Aqua boss is in the Team Aqua Hideout northeast of Lilycove City. You will need the HM move Surf to reach the hideout.
the hideout of magma/aqua is just north of lilycove but you must use surf from the east
Team Magma`s hideout is where you go down from the cable car east of lavaridge. Team Aqua`s hideout is on the East side of lilycove, you surf northeast to get there.
team magmas hideout is where you go down from the cable car, east of lavaridge. aqua is a surf north away from lilycove or mossdeep, i forgot sorry.
In the aqua's hideout
Team Aqua's hideout
beat their boss in slaterport
Team Aqua's hideout