Celebi is a Mythical Pokemon that can't be caught through any normal means in Pokemon GO.
The Time Travel Pokemon can't be caught in raids or in the wild. The only way to get one is to complete special research tasks all the way through to the end, which rewards players with a Celebi encounter.
However, there are only two questlines in the game that will lead to a Celebi, one normal and the other a shiny.
The normal Celebi can be caught at the end of the research task called A Ripple in Time. It's been in the game for longer than the second one, and it also has a longer questline in comparison.
There are 8 different stages for players to go through, and each stage has three tasks, which gives a total of 24 total tasks to complete.
Like many longer research tasks, they aren't about difficulty but rather about having the patience to acquire items and Pokemon.
The full list of tasks to get a Celebi in Pokemon GO
Pokemon GO Celebi quest: A Ripple in Time 1/8
- Power up Pokemon 5 times (1000XP)
- Battle in a Gym 2 times (1000XP)
- Battle in a Raid (1000XP)
Stage rewards: 10 Poke Balls, 1 Fast TM, 1 Super incubator
Pokemon GO Celebi quest: A Ripple in Time 2/8
- Make 3 new friends (1500XP)
- Evolve an evolved Grass type Pokemon (1500XP)
- Catch a Pokemon 3 days in a row (1500XP)
Stage rewards: 1 Sun Stone, 1500 stardust, 1 Premium Raid Pass
Pokemon GO Celebi quest: A Ripple in Time 3/8
- Use a Sun Stone to evolve Gloom or Sunkern (2000XP)
- Reach Level 25 (2000XP)
- Hatch 9 eggs (2000XP)
Stage rewards: 1 King’s Rock, Eevee encounter, 1 Premium Raid Pass
Pokemon GO Celebi quest: A Ripple in Time 4/8
- Evolve Eevee into Espeon during the day (2500XP)
- Walk 10km with Eevee as your buddy to earn candy (2500XP)
- Send 20 gifts to friends (2500XP)
Stage rewards: 1 Metal Coat, Eevee encounter, 2500 stardust
Pokemon GO Celebi quest: A Ripple in Time 5/8
- Walk 10km with your Eevee as your buddy to earn candy (3000XP)
- Evolve Eevee into Umbreon at night (3000XP)
- Trade a Pokemon (3000XP)
Stage rewards: 1 Star Piece, 15 Pinap Berries, 1 Upgrade
Pokemon GO Celebi quest: A Ripple in Time 6/8
- Visit PokeStops 7 days in a row (3500XP)
- Use 25 Pinap Berries while catching Pokemon (3500XP)
- Use items to evolve Pokemon 2 times (3500XP)
Stage rewards: 5 Silver Pinap Berries, 1 Dragon Scale, 3500 stardust
Pokemon GO Celebi quest: A Ripple in Time 7/8
- Catch 40 Grass or Psychic Type Pokemon (4000XP)
- Make an Excellent Curve Throw (4000XP)
- Earn a Gold Johto medal (4000XP)
Stage rewards: 10 Silver Pinap Berries, 1 Charge TM, Celebi Encounter
Pokemon GO Celebi quest: A Ripple in Time 8/8
- Catch Celebi
Stage rewards: 5,500 stardust, 1 Super incubator, 20 Celebi candy
The final stage is all that players need to complete for the quest line to be finished for good. By the end, players should have plenty of rewards as well as a Celebi in their collection.