Sootopolis City
In Pokemon Ruby and Sapphire there is no battle between Kyogre and Groudon. That is only in Emerald version. Instead the legendary pokemon (in your case Groudon) is inside the cave of origin in Sootopolis City.
you beat Archie on emerald
You can't get Kyogre in Pokemon Ruby but you can get Kyogre in Pokemon emerald and sapphire and in ruby you only get groudon and rayquaza. In sapphire you get Kyogre and rayquaza and in emerald you can get groudon, Kyogre, and Rayquaza.
groudon,kyogre,rayquaza
You don't
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.
In what game? In Ruby, Groudon is n Cave of Origin, before Rayquaza In Sapphire, Kyogre replaces Groudon. In Emerald, Groudon is in Terra Cave and Kyogre, Marine Cave.
No, you need to get Ruby. Or you can get Emerald where you can get both Kyogre and Groudon, including Rayquaza.
sootopolis city
Kyogre,Groudon, raquaza, Latias and (or) Latios
Yes, you can!
Rayquaza, Kyogre, and Groudon