There isn't one, you have to go the other way.
Dialga is not behind the waterfall all that is there is Dratini and Dragonair You find Dialga in a hidden cave in the wall on the east side of it. Love to answer your questions!!!!!
he isn't blocking the doorway to Dialga. you have to battle your way to the seventh floor, the Spear Pillar, and there will be a battle with the Team Galactic boss, followed by the professor's arrival, and then you will battle Dialga
if you are talking about diamond then no
you do need hm waterfall for mt. conet.There's a waterfall in mt.conet
You need to first defeat Cyrus (galactic boss) at the top of mt. coronet, then dialga. After that the person blocking the way shouldn't be there anymore
After you catch Dialga or Palkia, I believe you will get sent to your house. After you leave, go to the place where the hotel and pool is near Pastoria. The man blocking your way will not be there and you can go to Sunnyshore City!
You must go to the cave where you capture either dialga or palkia, get them(optional), and then the guy will let you through.
Beat the final gym and you will get the TM Waterfall. When you have this, teach it to your Pokemon and go up Mount Coronet towards the Spear Pillar and there will be a cave with a waterfall in it go round to the waterfall and go into the small cave at the top. The there will be 2 item balls. Get both of them and go to the spear pillar. Dialga and Palkia should then appear.
in mt coronet there's a secret door use surf use waterfall its in there
The only way to get past that man is if you go to Mt.coronet and catch either palkia or dialga(depending on your game of course)After that,the man will be gone.
You Have to go to mt coronet and you have to go to the top of it and battle/catch palkia/dialga and then the guy wont be blocking the way no more hope this helps
to find dialga you first have to beat the elite four then you have to go the same way you went to get giratina but stopping in one of the caves with the waterfall use surf then waterfall then theres a little cavern there you'll find the abdnant orb and lustrious orb those are necessary to find dialga then keep going to where you found the portal and there will be a blue light that is dialga your best bet is to go at night and use a dusk ball to catch it I've used this method my self dialga will be at level 70 so bring one equal to it it is a rock/dragon type but then if you go out and back in you can catch palkia also