When you get to the ruins
Cyrus is the team galactic boss and the player encounters him in many location during the course of the game. The final confrontation with Cyrus in Diamond and Pearl is at the top of Mt. Cornet when he tries to summon Dialga and Palkia.
you have to beat team galactic at their HQ
you need to fight the glactic boss at their h/q then go to spear pillar [mt cornet] and fight him again
When you have been all three lakes and had a chat or battle with all three team galactic commanders then the galactic boss in the Veilstone team galactic headquarters building the picture will be gone
Sorry if i get this wrong but i think mt. cornet
mt. cornet
you dont need them to
the one beside celestic town
the 1st time u go through mt cornet u meet him
get to the top of mt. cornet and you battle team galactic then go into the reverse world
you go to the oroburg entrince to mt cornet and use rck clime
At the peak of Mt. Coronet.