How to Get Celebi in "Pokemon Platinum"by C.J. Burry ; Updated September 22, 2017
The “Celebi” Pokémon is a special Pokémon found in “Pokémon Platinum.” It is a legendary-level Pokémon and one of the most powerful ones in the game. Though he is rare and difficult to obtain, Celebi can be encountered at random in “Pal Park,” a special area of Platinum where you can obtain many rare and legendary Pokémon. Before you can find Celebi, you must first fight 100 Pokémon. This is so lower-level characters cannot get this legendary Pokémon too soon.
Fight 100 Pokémon. This can be done by walking around and fighting in random encounters or by playing the game and fighting in gyms.
Go to Pal Park.
Wait until dark. This will take roughly 10 minutes in game time.
In the northern corner of the park, stand next to the far right tree and press “A.” You will then encounter Celebi and have a chance to capture it.