you don't. you get groundon on soulsilver and kyogre in heartgold. the only other way is to possibily cheat, but im not sure if that works.
You can't in Soul Silver, only in Heart Gold.
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.
I used Kyogre, Blaziken, Raichu, Dragonite, Mewtwo, and Ho-oh for battling the Elite Four for a second time. Nobody fainted. I barely used any hyper potions. You may have a better group in mind, but this worked out fine for me.
NO
In the Whirl Islands.
Cyndiquill!
Mewthree doesn't exist!
i would say soulsliver becase on soulsliver you can fly and black you cacth water pokemon but on sliver you can get fire pokemon
Surf in route 55
Meteor falls isn't in Soulsliver
it isn't anywere
Yes