you're gonna need to keep climbing mount coronet. there was a path that you couldn't get to before because you didn't have waterfall. it's in one of those caves in the snowy mountain tops on the way up. but in there you'll find adamant orb and lustrous orb. you'll need them to see dialga and palkia.
did you come from the north eastern oreburgh side? you'll need pokes with rock climb, strength, surf, and rock smash.