Alright the gameing master here is going to tell you a few tips for catching the legendaries in pokemon Sapphire and Rubyso here we go.
Making the Legendary Regi's Avalible
Well the first things you need are Relicanth and Wailord. Then head to Pacifidlog Town and start to surf west.Once you hit strong currents dive down.Under water you'll find letters in Braille
Put Relicanth as your first Pokemon and Wailord as your last. Then press on the slate in the Braille to cause an earthquake. This unlocks the three Legendary Regis Pokemon so you can capture them.
Capturing the Legendary Regice
To catch the Regi-Ice Pokemon, head to Dewford Town and surf north. Find the guy on an island with trees all around him. Head left and up 'til you find an island with a mountain. Head into the mountain, find the Braille wall and press A in the middle of the wall. After a few minutes a door to the Regice will open and you can go catch it.
Capturing the Legendary Registeel
To catch the Regi-Steel Pokemon, head to the Safari Zone but, instead of entering, go left upstairs and then north 'til you find an area that's raining. There's another cave with Braille in it here. Use Fly in the middle of the cave and you'll find the Registeel in the next room
Regirock
For Regirock go to the desert near Mauville City and go all the way down, and to the cave go inside. Read the braille then where you are standing go Right, Right, Down, Down then use Strength. The door should open. Go through and a L40 Regirock will be standing in the middle of the room.
Latios And Latias
You're after Latios and Latias in Pokemon Sapphire for the GBA? Then I have good news and bad news for you! The bad news is that Latios is only in Pokemon Ruby and Latias is only in Pokemon Sapphire, so you won't be able to catch both Pokemon.
I have some game hints, tips and cheats that'll help you to catch Latias in Pokemon Sapphire though! Here's how you do it:
Finding Latias In Pokemon Sapphire for GBA
The first trick to catching a rare Pokemon is to know where to look. Latias hangs out in the Hoenn area of Pokemon Sapphire so that's a good place to start. Once you're there, Latias rarely shows up unless you have a Pokemon that's at least Level 80. If you're still having problems finding Latias, fly around Mossdeep City until you see it in the water. Then, land near where Latias showed up and start searching.
Catching Latias in Pokemon Sapphire for GBA
Battling Latias is even trickier than finding it! The best attack against Latias is the 'Mean Look' attack, the Sableye Pokemon is really good at that. Hit Latias with one of those to weaken it, and then start tossing Pokeballs at it to try to catch it. If you have a Master Ball, use it, otherwise it'll take a whole bunch of tries. Latias also runs away a lot, and uses a power that knocks itself out. If it runs away, it keeps any damage you've caused for next time you battle it, so be careful
Catch/find Latios
First get some Ultra balls. (If you have a Master Ball that is great!) Fly to Mossdeep City and surf up North. Latios should show up within five minutes.
When you're champ, go to Mossdeep into Steven's house and there will be a Beldum on the table. Take it as Steven gives it to you.
Rayquaza
when you have already beaten the Pokemon League, fly to Pacifidlog Town and then surf east for a while. Now go North, and then West. You will find a building called Sky Pillar. You must have the Mach Bike. You will find out why- keep going up the stairs and you will find a Pokemon called Rayquaza at level seventy.
Jirachi
There are 4 known ways to obtain Jirachi in R/S:
*The first way is by having in your possession a Pokemon: Colosseum Bonus
Disc. You can get Jirachi from it. (you'll need a GBA-Gamecube link, and of
course, a Gamecube)
*The second way is this: If you have a European or Australian Pokemon Channel,
you can download Jirachi from it after completing the game.
*The 3rd way is by obtaining it from a Nintendo event. (I hate it when they
do this. The event, of course, already happened)
*the 4th, easiest, and fastest way to get Jirachi is to use a Gameshark or Action Replay.
...........And thats how to get Jirachi and the other legendaries in Pokemon R/S