HM7 contains the move Waterfall.
in the cave of origin
HM08 Waterfall is in the Cave of Origin in Sootopolis City.
In Soothopolis, inside the Cave of Origin, where you catch Groudon
You cannot go through waterfalls but you can climb them with the HM waterfall and a Pokemon that can learn it... you will also need the corrosponding gym badge
You go around the ocean until you find a waterfall, then you go up the waterfall with HM07.
Learn waterfall and go to EverGrande city
in the cave in sootoplis city when your going to fight groundon
cave of origin. sotopolis city when you need to fight groudon
really rare in meteor falls need surf and waterfall to get to where bagon is
By itself:only goldeen,seaking With Tm:Mostly any water or dragon pkmn
I found it in Cinnabar Isle.. Where you get a sun stone i believe