How do you get to mount coronet?

mt coronet i what seperates sinnoh in 2 parts, its between heatrome,oerbirgheterna and celestic city (celestic town) to get tthrough there u need HM3(surf) HM4(strength) HM5 (defog) HM6 (rock smash)...

You need to go in via the Hearthome entrance, use surf and rock climb. Then follow the path up.

it changes evryday its really annoyin and hard 2 get lol

if you mean 2nd floor in spear pillar, you need an item that hasn't been released in an event though. if you search you might find a cheat for it. At the top is arceus at level 70 or 80. (masterball...

release the lake Pokemon in the Galatic HQ building