Instructions
Defeat the "Pokémon Ranger" game. You must destroy the three legendary dogs, Entei, Suicine and Raikou, in the last battle of the game before you can access Celebi. Press "R," "X" and "Left" at the same time to unlock Ranger Net during the end credits. Your game will be saved after the end credits.
Turn on "Pokémon Ranger" again. Access the main menu during game play and select "Ranger Net." You will see listings of special missions. You must first complete the "Gain Deoxys's Trust?!" mission. Select it. You will encounter Deoxys in Krokka Tunnel, where you must battle it and capture it only when it is in its normal form.
Complete the "Gain Deoxys's Trust?!" mission. Open the main menu again and select the "Rescue Celebi!" mission. Travel to Lyra Forest to find Celebi. According to the storyline, the Go-Rock Squad is on a mission to capture Celebi, and it is the player's responsibility to capture Celebi first. Lyra Forest is located in the Fiore region, south of Krokka Tunnel and north of Ring Town.
Watch the cut scenes in Lyra Forest when you first spot Celebi; when they finish, you will enter into battle with it. Use a Fire-type Pokémon for the best odds against Celebi.
Touch your stylus to the screen and draw a loop around Celebi with it. A blue line should trail your stylus, and the edges of the loop you draw should connect. A number will appear over Celebi's head; this number indicates how many more loops you need to draw around Celebi to capture it.
Draw the number of loops around Celebi required by the number above its head. Remove the stylus from the touch screen to capture Celebi.