You can't in Soul Silver, only in Heart Gold.
Yes. Kyogre is the main legendary Pokemon in Sapphire.
In HeartGold you can catch Kyogre.
kyogre,groudon,raquaza and jirachi
Kyogre only.
The two games are essentially the same difficulty. The only major difference is that in HeartGold, you can catch Kyogre, while in SoulSilver, you can catch Groudon.
Best non-legendary water pokemon would be Gyarados. Best legendary water pokemon is Kyogre.
There both the same game but in Heart gold you can catch Ho-oh and in Soul Silver you can catch Lugia. So they both have the same pokemon. If you like the Pokemon Kyogre, you can catch one in Pokemon Heartgold. If you like Groudon, you can catch one in Pokemon Soulsilver.
you only can trade it from heart gold. you can catch groudon on soul silver
Battle the legenary red than catch kyogre
In order to catch your legendary Pokemon in Pokemon Sapphire, save your master ball For Rayquaza...you can catch KYogre/Groudon/both with either an Ultra Ball or Timer Ball.
You can't catch kyogre in Pokemon soulsilver.
Hatch? No. No legendary Pokemon can be bred in any Pokemon version. You can catch Kyogre in Sapphire though ;)