Celebi is a green, fairy-like Pokémon. It has round toeless feet, three-fingered hands, and clear wings on its back. It has a round head that comes to a curved point. It has large baby-blue eyes with thick black rings around them, and a pair of green antennae with blue tips.

Often found in forests, Celebi is known in legends as the "Voice of the Forest." It is able to travel through time and exist simultaneously throughout time, and plant life flourishes wherever it has been. As seen in Pokémon 4Ever - Celebi: The Voice of the Forest (M04), said plant life is able to heal Celebi when it is dying and restore the flora around it to perfect health. Celebi also has the ability to heal wounds, and can release a telekinetic energy wave to defend itself. It was shown in Pokémon Colosseum that Celebi has the power to instantly purify Shadow Pokémon and can be summoned at Relic Forest with the melody of a Time Flute. Despite living in forests as its guardian, Celebi only shows itself in areas and times of peace. It has been regarded that as long as it is seen throughout the world, a prosperous and bright future is still in store for the Pokémon world. As depicted in A Timeless Encounter! (SM125), Celebi can sense if something is a temporal anomaly in the current timeline and will bring them back to their original timeline. It has been referred to as a forest deity.

(Source: Bulbapedia)