You Can't! in Soul Silver you can but in gold you catch Kyogre
You can't Find Him on Pearl he can be traded from Heart Gold or Soul Silver but you can't catch groundon on Pokemon pearl i hope i helped. :)
after you beat the game go to mister Pokemon and he will give you a red orb for soul silver and a blue orb for heart gold and then go to the embbed tower
gold is from joto and groundon is from hoen if you want groundon play ruby,Sapphire or emerald
you don't get groudon in heart gold. if you have soul silver, you have to get 16 badges, the red orb at Mr Pokemon's (aka: professor oak's) house above cherry grove town
to get a kyorge in soul silver you have to trade with some one how has kyorge in Pokemon heart gold after you show prof. oak both kyorge and groundon he will give you a jade orb to catch rayqauaza!
It's Darkrai. You can't get him in Heart Gold.
Pokemon Heart gold is different from Pokemon Gold cuz heart gold has better graphics new Pokemon and new events
really it dose not matter because the only different is that in heart gold you will get hoho at lvl 50 and get lugia at lvl 70 and in soul silver you get lugia at lvl 50 and ho ho at lvl 70 and you get groundon at lvl 50 in soul silver and kyogre at lvl 70 and in heart gold kyogre at lvl 50 and groundon at lvl 70 o and one other difference is that you get latios in heart gold and latias in soul silver.
First you have to beat Pokemon Trainer Red. Then you go to Professor Oak and you get either bulbasuar, charmander or squirtle. Then you go to Mr. Pokemon and he gives you a Red orb if you have Soul Silver or a Blue orb in Heart Gold. Then you fly to the Embedded Tower and find Kyogre in Heart Gold and Groundon in Soul Silver. Then you have to transfer a Groundon (if you got Kyogre) or a Kyogre (if you got Groundon) into your game. Then you go to Professor Oak with them both in your party and he will give you a Jade Orb. Then Fly back to the Embedded Tower to find Raquaza!!! -Game Champion
in heart gold of soul silver after tyou beat the game talk to mr. Pokemon and he'll give you a blue orb (in heart gold)or a red orb (in soul silver) and go to the embedded tower(you will ned a Pokemon with surf and rockclimb)it is by the safair zone and if you have your orb in your key items when you go in you should see(depending on the game and orb) groundon or kyoger. if you have both groundon and kyoger (they have to be caught form heart gold and soul silve) you go to pallet town in kanto and talk to proffeser oak and if you have both a kyoger and groundon from heart gold and soul silver both of them should be at the front of you party and when you talk to him he will give you a jade orb go back to the embedded tower and rayquaza will be there for more info go to bulbapedia.bulbagarden.net and seach for Pokemon,items,games,places, and more it will tell you where to find a Pokemon and what item needed (if you need an item),the moves it learns and what level or thy serebii.net or pyspoke.com
If you have Pokemon heartgold, you cannot get groundon unless you trade with someone who caught a groundon on soul silver. PS- It has to be from the embedded tower, any migrated groundon will not work.
Gold and Silver: you beat the game Heart Gold and Soul Silver: you can get Kanto Starter from prof. oak, Heonn starter from steven at saffrom city. And you can get Kyorge HG Groundon SS from Mr. Pokemon route 31 i think