The Celebi event for HeartGold and SoulSilver has already came and went. It started on February 21, 2011 but it ended on March 7, 2011. There is no chance of the Celebi event download for HeartGold and SoulSilver repeating so the only way you can get the event Celebi is by trading for it.
you get it by an event.
You need to have the Celebi event. it is over. sorry
No, it is not possible to do the event in HeartGold and SoulSilver with any Celebi because the game reads what is encoded in Celebi's summary. You need a Celebi with a "Fateful Encounter" flag on it (this flag will be shown in its summary) in order to unlock the event in HeartGold and SoulSilver.
Nope has to be the special event Celebi in HeartGold and SoulSilver
in HeartGold + SoulSilver, it is the mew event, then the celebi event, then enigma stone for latios/latias.
I'm afraid you cannot get a Celebi in Pokemon HeartGold, unless you use a Action Replay. The only Celebi legal, I think, is the Nintendo Event that has passed. If you do have the Celebi in your GameBoy Pokemon Cartridge, then you can migrate it to Pal Park, then trade from Pearl/Diamond to HeartGold/SoulSilver.
You cannot CATCH Celebi on Pokemon HeartGold or SoulSilver, but there is an wifi event a Gamestop that gives you a Celebi in mystery gift. You can also use a Action Replay™, but I suggest you do the event.
Celebi cannot be caught in Pokemon SoulSilver. Celebi can only be obtained through an event or Action Replay cheat. Celebi cannot be found in HeartGold, either.
You can get a Spiky-eared Pichu in Pokémon HeartGold and SoulSilver if you get the movie-event Pikachu-colored Pichu and bring it to Celebi's Shrine in Ilex Forest in HeartGold or SoulSilver.
Hopefully soon. The makers are planning to make an event for celebi in Heartgold/soulsilver. I heard that Gamestop Stores in the US may be doing a Celebi Giveaway sometime in May, 2010, but I"m not sure.
You literally can't. There was an event where you could get a celebi from gamestop sent to your Diamond, Pearl, Platinum, Heartgold, or Soulsilver, and that celebi could be transferred to white, but the event ended on March 6, 2011.