I think you have to complete your pokedex because Oak say you habe to complete your pokedex. You need to show hime 386 Pokemon or more.
There are many legendary Pokemon in emerald, such as groudon, rayquaza, groudon, deoxys, and such. Groudon and Kyogre are not available until after beating Wallace, but Rayquaza can be caught right after the major battle between groudon and kyogre.
you go back to the cave where you caught groudon/kyorge
Catch rayquaza at the same place you caught groudon!
You need both Kyogre and Groudon in your party. Bring them to Professor Oak, and he'll give you a green orb. Bring that to the same place you caught Kyogre/Groudon and Rayquaza will appear.
you trade kyorge from heart gold and go back to the place you caught groudon
To get rayquaza, you need to get groudon+a kyogre and then go to the man where you got togepi from and then you will receive a green orb then go to the place where kyogre/ groudon was and then catch it. I've got groudon and now all I need now is kyogre. I also caught zapdos with one ultra ball
Rayquaza is obtainable in HeartGold and SoulSilver by getting Groudon AND Kyogre on one game. Then you have to show them to Professor Oak. He will give you the Green Orb. Once you have the Green Orb, go to the Embedded Tower where you caught Groudon/Kyogre. Rayquaza will be there.
Heart Gold:First, you must catch Kyogre. Afterwards, have someone trade you a Groudon from their Soul Silver game (must be from Soul Silver, otherwise it won't work). Show both Groudon and Kyogre to Prof. Oak. He'll give you the Jade Orb. Take it and go back to where you caught Kyogre. Rayquaza should be there.Recommended: Save your game before battling Rayquaza if you wish to capture it, in case you kill it or it kills all your Pokemon or you run out of Pokeballs.Soul Silver:First, you must catch Groudon. Afterwards, have someone trade you a Kyogre from their Heart Gold game (must be from Heart Gold, otherwise it won't work). Show both Groudon and Kyogre to Prof. Oak. He'll give you the Jade Orb. Take it and go back to where you caught Kyogre. Rayquaza should be there.Recommended: Save your game before battling Rayquaza if you wish to capture it, in case you kill it or it kills all your Pokemon or you run out of Pokeballs.
You get a person who caught a Kyogre in Heartgold and trade it over. Then you talk to Prof. Oak and he'll give you the Orb to get Rayquaza in the Tower you caught Groudon in. Note that a Kyogre not found in the same place as Groudon will not make Prof. Oak give you the Orb.
after u defeate elite four and caught rayquaza,fly to the weather institute talk to the guy who gave u castform,then he'll tell you where he is,go and fine him then catch him,GOOD luck . :)
Trade from another game.To find Rayquaza at the Embedded Tower you must show Professor Oak a Groudon and Kyogre caught at the Embedded Tower. The Embedded Tower is new to HeartGold and SoulSilver. In HeartGold you catch Kyogre but cannot catch Groudon and vice-versa in SoulSilver, so you must trade with someone who has SoulSilver for a Groudon then show that to Professor Oak. If the Pokemon is not caught at the Embedded Tower then it won't count.
Ho-oh, lugia, latias, raikou, suicune, entei, moltres, articuno, zapdos, mewtwo, kyogre, rayquaza( groudon caught in soul silver)