The second to last answer I made:
Lugia: Whirl Islands
Ho-oh: Bell Tower
Entei / Raikou: Roaming Kanto
Suicune: Chase it around certain spots, eventually ending up at Bill's house.
Latios: Roaming Kanto
Latias: Available by event only
Kyogre: Available by trade only
Groudon: Embedded Tower
Rayquaza: Embedded Tower (after you have both Kyogre and Groudon)
Articuno: Seafoam Islands
Moltres: Silver Cave
Zapdos: Power Plant
Mewtwo: Cerulean Cave
Dialga / Palkia / Giratina: Available by event only
Latios
Well, I guess you mean "Soul Silver", and the main legendary Pokemon is Lugia, Water/Flying-Type.
the only legendary that you can breed is manaphy. and that will result in a phione.
over 9000
to get the legendary (lugia) you must go to the whirlpool islands and on one of the islands you will find lugia
Probably either Mewtwo or Rayquaza.
ranges from 40(legendary dogs) to 70(ho-oh for you, mewtwo, ect.)
you have to look in places where a legendary might live (example: Zapdos=power plant)
Well I have the game so once
yes. but there very hard to find.
yes you do in fact you need it to get most of the legendary pokemon.
Moltas: the fire legendary bird Pokemon the second strongest bird Pokemon