Yes, you can!
You don't
no
You have to catch Kyogre and Groudon.
not much only in sapphire you can only catch kyogre and in emerald you can catch both kyogre and groudon.
you can`t catch kyogre or groudon or both of them without linking them from sapphire, ruby or emerald version.
yes after beating the elite 4 you can catch both him and groudon.
Yes, You can catch Groudon in Pokemon Emerald.
there are three that you can CATCH in pokemon emerald its Groudon, Kyogre, and rayquaza regice registeal regirock litos lotias
Rayquaza, Kyogre, Groudon, The Regis, Latios and Latias, and a lot more.
Rayquaza, Groudon, Kyogre, Regirock, Registeel, Regice, Latios/Latias.
rayquaza,groudon,kyogre,regice,registeel,regirock,latios or latias.
Its impossible to catch any hoenn Pokemon in firered if you want hoenn Pokemon like groudon and kyogre trade them from ruby, sapphire or emerald to receive them in firered.