the guy at the weather institute will tell you whether it is raining or there is a drought and when he says it is raining go to the route or place he tells you and dive there then you can go catch it
not much only in sapphire you can only catch kyogre and in emerald you can catch both kyogre and groudon.
I do not know if you can catch Kyogre in Emerald but if you could, Kyogre will be in the Cave of Orgin at Sootopolis City. ;) ANSWER At marine cave, but I dont know how to get there
you cant
You don't
you can only catch rayquaza in emerald, but if you have ruby and Sapphire you can trade gruodon and kyogre into emerald.
No You need to trade it from sapphire or emerald
Yes, you can!
It is in the sky pillar
Get one from sapphire or emerald.
No You need to trade it from sapphire or emerald
You cannot catch Kyogre native in Pokemon Diamond. You must import the mighty Kyogre from Emerald or Sapphire using Pal Park.
no