How to Get Groudon

1. You need 7 Gym Badges just like Kyogre. Go to Brimber City and talk to the Gym Leader again and you will have to battle him again but he has a different team this time.

2. Once you defeat him, go to Mt. Igneus and find the pedestal. Once you found the pedestal, a cutscene will begin of your character placing the red orb on the pedestal and Groudon will then emerge and you will be able to catch/fight him! 

ONCE YOU GET GROUDON YOU GET THE RED ORB FOR PRIMAL AS WELL.