This code works similar to the Coin Case ACE code by changing species byte 2 of Pokémon 1 (so when the Pokémon is taken into the Day Care and out it will become Celebi). If used with an Egg, the Egg will hatch into a Celebi although I don't know if its starting moves will be changed. If they aren't changed I'll look into making codes for modifying the Celebi to have its starting moves for you.
I've looked into the Celebi methods quite a bit and I'd thought I'd mention the few methods I've seen that enable a Celebi with its start moves (which I see as a completely ''legit'' Celebi given it will learn it all it's moves then and it's start moves are unique compared to most Pokemon, Heal Bell, Leech Seed and recover being pretty rare moves).
Just wanted to share this for a bit of discussion and in case not everyone is aware, hope it's not too off-topic though..
Anyway the oldest method is the bad clone Celebi egg glitch method which has a few videos on YouTube, this one being the most recent: https://www.youtube.com/watch?v=RFo6Colpc2k
This method is hard to perform though and can corrupt your save file if something goes wrong, I've attempted it before but wasn't successful.
A more newer method Crystal_ posted, shows obtaining any Pokemon through ACE and the bug catching contest: https://www.youtube.com/watch?v=a0ZZ3rIL0vA
And I recently came across this video the other day which shows obtaining Celebi through it's easiest method with the coin case in Gold/Silver, but then through ACE teaching Celebi it's start moves: https://www.youtube.com/watch?v=KdpbBYio-T0
Definitely think this video should get more exposure, it's a good one.
Basically: Any Celebi obtained at level 0 will learn it's start moves after giving it a Rare Candy. Obtaining Celebi through the easiest coin case method, the lowest you can obtain it is level 2 therefore it doesn't learn them. If you use a egg and obtain Celebi at level 5 it won't learn them either, but as shown in the last video you can teach Celebi the moves now. Celebi obtained through the Ilex Forest event at level 30 has Heal Bell, but none of it's other start moves.