You have to beat the 6th gym, Roark's father, then you shall be able to use the ROCK CLIMB to eventually get to the point where you are able to fight team galactic for Dialga or Palkia at spaer pillar which is located at the top of Mt. Coronet.
beat the #?*@! gym leader
what did you say
the best way to beat the 7th gym leader is with a fire type Pokemon
With good Fire of Fly Pokemon!
train your Pokemon to about lv 20
you beat the gym leader
beat the 2 gym leader
just beat the fourth gym leader
Beat the first gym leader: Roark.
Use a fire pokemon. That's what grass is weak against.
You beat the first gym leader, Roark in Oreburgh City.
You have to beat the team galactic leader, then dialga comes out.