You first have to beat Mt.Battle in story mode. Then, buy an E-card. You slot it in and then you go to the E-card room. Your team must be full of 3 fire type pokemon, and 3 water type. Talk to the cooltrainer, who is dressed like a clerk. Then, a lady cooltrainer will join in with the boy and helps you in the door. Once you're in, there will be a room. Once you go out now, it is possible to catch a shadow scizor, shadow flaafy, and a shadow togepi from trainers. As for groudon and kyogre, you have to catch all of those shadow pokemon I mentioned above. Once, you're on your journey to the last one, a trainer will prank call your P*DA and will tell you to meet at Phenac City near the mayor's house or office, whatever! It will turn out as Evice, the guy who went in jail ealier. He will call his helicopter and he will escape. You can now fight Evice in the realgam tower colosseum. He will have a level 57 shadow groudon. As for kyogre, you have to fight him again. I recommend you use a timer ball or a ultra ball. This whole thing was pretty much a prank!!! I LIED TO YOU! YOU CANNOT GET THOSE POKEMON IN THE GAME!

no u cant. sad aint it? u have to trade from pokemon emerald(u get both of them in emerald), ruby(u only get groudon) and sapphire(u only get kyogre)

hope that helped!