Which waterfall? If it's the one in Tohjo Falls, you have to obtain all gym badges, teach a Pokemon Waterfall, and climb up the waterfall into Kanto. If it's Lugia's chamber, then there is nothing else after you catch Lugia.
Beat the last gym leader then go to the girl in front of 223 water road and she will give a HM for going past the water fall.
the first time you walk in the cave i think its there. that's what i did
Teach one of your Pokemon the HM Waterfall, and you can go up the waterfall.
use the move waterfall from the ice path. defeat blackthorn gym leader Clair to use it in the field
get all HMS and flash
If by that you mean one short through one route then yes. Go to the Cherrygrove City healing center.
You get the Spearow at Route 35 and you give it to the guys friend at Route 31
Between Viridian City and Victory Road... What about route 23? Is there even one?
the Friday girl should be at the same place she was in Pokemon crystal (the one i played) which is the route just before you enter the union cave, after violet city. hope this helps =D
To catch a Metapod in Pokemon SoulSilver (And in Pokemon HeartGold as well), you have to enter the Bug Catching Contest at The National Park on Tuesdays, after you obtain the National Pokedex.
Waterfall can be found on route 18
HM05 Waterfall is found on Route 18.
HM Waterfall can be found on Route 18 in Pokemon Black and White.
You get HM Waterfall at the end of Route 18 on the strip of grass in Pokemon Black.
Go to Ecruteak City and then proceed east on Route 42 until you reach Mt. Mortar. Be sure to bring along a Pokemon that knows Surf, and possibly Waterfall.
route 18
On route 18
on route 18
Route 18. Far West of the route.
go through route 42
you get it in route 18
HM05 Waterfall is on Route 18.