I am afraid you can not.
special events
no. only events
Well 1st of all your a dork because you missed they event
A hack of Pokemon SoulSilver that makes the game harder and adds new Pokemon not in SoulSilver, along with new game events.
6.
by using wifi or wireless at a certain place
no they do not
Celebi is only available through special Pokemon Events.
It's impossible to get without certain events/Hacks. Sadly, all of the events are over.
Action replay or Nintendo events
there is no event for manaphy you have to get it from Pokemon ranger
They are special events at stores like Toys'R'Us and GameStop. Special Pokemon like Arceus, Darkrai, and Celebi are distributed through them.