Currently, Celibi is not available in Pokemon Soul Silver. At some point in the future, Nintendo may release Celebi at special events, however if you have another Celebi from a different event on another game (GBA series/Diamond/Pearl/Platinium) you can trade it onto Soul Silver/use Pal Park with the Dual Slot feature.
Alternatively, you could try looking at the Global Trade Station if you have a Wi-Fi connection.
Catch dragon type pokemon.
you need to learn how to spell.
you wake him up with the pokeflute
Missingno. only exist in red and blue.
you battle celibe level 5
you transfer one from Pal Park or Pokemon Sappire, Ruby or Emerald
Teach the HM Strength to one of your Pokemon and use Strength on the boulders
just send celibe as a mystory gift to anthor ds and resive celibe
you cant
the seventh gym leader is in the island where articuno was in and still is
From an event.
you cant until you get to rout 15 and it tell you how to trade in your instruction booklet, just look in the index