Where do you get water fall And how do you get to sunny shore?

You can get to Sunyshore by beating/capturing Dialga/Palkia on the top of Mt. Coronet. You get Waterfall in Sunyshore, after defeating Volkner. You get it from Jasmine, the girl in the small beach.

You have to go to the top of Mt. Coronet and defeat/catch Dialga. This can be done once you've obtained the 7th badge and visited all 3 lakes, and you've found your way through Team Galactic's Warehouse and HQ in Veilstone. When you've done all this, you can get to Sunnyshore City.
In Sunnyshore City, once you've obtained the 8th badge there, you can get HM07 Waterfall from Jasmine at the north end on the beach.

Beat the 8th Gym Leader and talk to Jasmine on the beach at the north end of town. To get to Sunyshore, catch or kill Dialga

Ok. When I hadn't beaten the game, I had this question too. In Canalave city, you go to the library once you have beaten the gym. Your rival will take you there. You will go up the stairs, and meet up with Professer Rowan and Dawn. He will talk about the three mirage Pokemon (Uxie, Azelf, and Mesprit, if you didn't know) and how they connect to unvealing secrets about Pokemon evolution. He tells you to go to Lake Valor. Then, an earthquake starts. You all go outside, and Rowan will tell to get to that Lake. Go there, and beat Saturn. Once you have, he will talk about Mars and Lake Verity. Save your hometown as soon as possible and go to Lake Verity. Then, you battle Mars. Once she's beaten, she will tell you that Lake Acuity is under attack. Go to Celestic town and go left, entering Mount Coronet. Once out of there, you find yourself on route 216. Then you continue to go left then up. On the way you should find HM08 Rock Climb. When you first get to the Acuity Lakefront, two Galactic Grunts will be guarding the enterance to the lake. So, go right to Snowpoint city. Beat the gym, and go back to the lake. The grunts will be gone. So, enter and help out your rival. Then, you find out he was beaten. So, Jupiter will tell you some things and leave. Go to Veilstone and find the grunt near the Galactic building. Talk to him, he seems to be freaked. He runs after awhile and drops the Storage key. Then, you must find your way through the puzzling building. You have to beat Cyrus. Then he gives you the master ball, lucky you. Yet, you have to save the three mirage pokemon. So, you have to battle Saturn again. Then press the button to set them free. You are then warped out of the building by stepping on the green panel in the previous room where you fought Cyrus. Then, you must head to Mount Coronet again. This time go to Orebrugh and take the route 207 path inside. Use the new rock climb on that patch of rock in the northeast corner. Continue ascending until you reach the spear pillar, where you are confronted by two grunts. Then you continue after defeating them and finding Mars and Jupiter. They want to battle you. Then, you guessed it, your rival comes at you. You double battle. He heals your Pokemon if you win. Then, Cyrus again. Once beaten, that red chain glows and Dialga comes. After some talking, youm battle him. Beat it or capture it. Your choice. Then everyone leaves, and you have to go all the way back down. Go to Pastoria and head right, and you will be able to get to Sunnyshore city. Once you beat the gym, go to the patch of sand in the north. The gym leader from so other region whose name escapes me gives you waterfall. Hope this helps!

Hyrules_Hero