As with most legendary Pokemon, Celebi is blessed with great base stats all around. It also has a good and synergetic typing, an awesome ability that lets it act as a status absorber, and a phenomenal movepool. These traits allow Celebi to play many roles, depending on your team's needs. It can be a sturdy special wall that handles many prominent threats, such as Keldeo, Thundurus-T, Sheer Force Landorus, and Breloom, with a large repertoire of utility moves, consisting of Stealth Rock, U-turn, Perish Song, Thunder Wave, Heal Bell, and Baton Pass. Or it can take the offensive route and utilize its good coverage, bulk, and resistances to set up with Nasty Plot, making it quite hard to wall. It can even use a Choice Scarf set to revenge kill troublesome threats, a Baton Pass set to assist your sweepers, or a tank set to combine the offensive and defensive roles.
However, the list of its flaws is as big as the list of its advantages. Its typing leaves it with a whopping seven weaknesses, one of them being a quadruple weakness to Bug moves. This means that it is prone to both Pursuit trapping and to U-turn, which is never a good thing. As with most Grass-types, it struggles quite a bit against sun teams, but don't let its flaws disappoint you. With the right teammates Celebi can really shine, and prevent those pesky rain teams that are everywhere from overwhelming you.
With its good stats, typing, ability, and access to Recover, Celebi is able to check a lot of threats, namely Keldeo, Thundurus-T, Sheer Force Landorus, Starmie, Rotom-W, Politoed, Calm Mind Jirachi, and Calm Mind Latias. Giga Drain is the standard STAB move that gives Celebi a bit of recovery, and allows it to hit the Water-types it walls for super effective damage. Psychic is the other STAB move that Celebi can use instead of Giga Drain, and has its own unique advantages. Psychic lets Celebi deal better with Pokemon such as Thundurus-T, Breloom, Tentacruel, Conkeldurr, and Amoonguss, while still hitting some targets of Giga Drain for super effective damage, namely Keldeo and Terrakion. However, when using Psychic, Celebi has a harder time against Water-type Pokemon that can hit it hard, such as Life Orb Starmie and Choice Specs Politoed, because it cannot damage them quickly enough and may succumb to a critical hit or a freeze. If dealing with Water-types more reliably is of utmost importance, then use Giga Drain, otherwise you are better off with Psychic, which is useful against a wider array of threats. Recover is used for reliable recovery, and combined with Natural Cure, makes Celebi very difficult to take down. U-turn is a good move for any defensive Pokemon, especially Celebi, allowing it to be an excellent pivot and to scout for any Pokemon looking to kill Celebi with Pursuit, such as Tyranitar and Scizor. However, Baton Pass is preferred to enable Celebi to escape from Pursuit without taking damage.
In the last slot there are three utility moves that can be used. Perish Song is a rare and useful move with shallow distribution and allows Celebi to counter many set up sweepers, such as Calm Mind Jirachi, Calm Mind Keldeo, Substitute Dragon Dance Dragonite, Calm Mind Latias, and Calm Mind Reuniclus, essentially acting as a phasing move. It also stops Baton Pass chains cold, and gives a win condition if your opponent is left with one Pokemon. Perish Song also synergizes well with U-turn, as when the opponent is forced to switch out, in the last turn of Perish Song, you can easily scout the switch-in with U-turn, gaining the upper hand. Thunder Wave is another excellent move that helps Celebi deal with a multitude of Pokemon. The ubiquitous Scizor loves to switch into Celebi, and Thunder Wave cripples it significantly. Same goes for Latios, Latias, Hydreigon, Kyurem, Kyurem-B, and Dragonite. Finally, Stealth Rock is always an option, and Celebi is one of the most reliable users of the move and finds plenty of opportunities to set it up, but many Pokemon learn this move, and you should better utilize moves that are semi-exclusive to Celebi, or help Celebi more with its role.Team Options & Additional Comments >>>
While this might look like a dedicated Baton Pass set, in reality, it is a variation on the standard specially defensive Celebi. With its excellent defensive stats, reliable recovery, and Grass typing, Celebi takes on Water-types in rain as well as anything. Baton Pass is already a decent move on defensive Celebi even with nothing to pass, as it acts like U-turn while also allowing Celebi to escape Pursuit, so giving it a boosting move only requires a small investment—just one moveslot. Celebi is easily walled by a variety of Pokemon, as it lacks offensive investment and has STAB moves with poor neutral coverage. This set allows Celebi to do some real damage—by letting something else do it instead!
As for which boosting move to use, that depends largely on your team. Nasty Plot is probably the best option, as Special Attack boosts are most useful to Celebi and Choice Scarf Keldeo is by far the best receiver available. Calm Mind might allow Celebi to set up multiple boosts, or at least set up on powerful special attackers at lower risk. Substitute is useful to a wider variety of Pokemon, but will usually be broken as Celebi passes. It's a lower risk, lower reward option. Don't forget, of course, that you don't have to use your boosting move every time you bring Celebi in. The priority should generally be to maintain Celebi's health such that it can continue to wall special attackers. Lastly, you need to choose which STAB move to use. With the exception of Tyranitar, Psychic typically does more damage to Celebi's counters, but Giga Drain is still a good option, as it hits Tyranitar and Water-types harder and the recovery provided is handy.Team Options & Additional Comments >>>
This set takes advantage of Celebi's good bulk and Special Attack, transforming it into an offensive tank. While at first glance it may seem inferior to Latias in the tank role, which boasts better typing, Speed, and coverage, Celebi is quite different due to its Grass STAB, Natural Cure, better physical bulk, ability to utilize Thunder Wave to a much greater extent than Latias, U-turn, Earth Power, and the ability to beat the most common Pursuit users, Tyranitar and Scizor. Leaf Storm is the primary move of the set and packs a lot of power due to the offensive investment, Life Orb, and STAB. The Special Attack drop might seem offsetting, as it makes Celebi set-up bait for a host of threats, but fits very well with this set's hit and run nature. Earth Power is used for coverage against Steel- and Fire-types, such as Heatran, Jirachi, and Ninetales, while hitting many Pokemon that resist Leaf Storm, such as Scizor, Forretress, and Volcarona for neutral damage. Psychic provides Celebi with a reliable STAB move to work with, while still covering some Pokemon that would want to switch into Leaf Storm. Some other targets of Psychic are Dragonite, Salamence, Breloom, and Thundurus-T (the latter two in particular are important as you can usually switch into them with little worry). Hidden Power Fire gives Celebi coverage against Steel- and Grass-types, the most important being Scizor, Ferrothorn, Breloom, and Forretress.
In the next slot an utility move of your choice is chosen, allowing Celebi to act as a great team player. Thunder Wave works amazingly on Celebi, as no Ground-type would want to switch into it, almost making sure that something is going to get paralyzed. Thunder Wave also incapacitates some of the most common switch-ins to Celebi, namely Latios, Salamence, and Dragonite. However, U-turn makes Celebi's checks and counters take damage from entry hazards and U-turn itself, while getting forced out by your switch-in. U-turn also deals pretty good damage to some Pokemon weak to it, such as Tyranitar, Latios, Latias, and Celebi, and helps mitigate the Special Attack drops caused by Leaf Storm. Another small benefit of U-turn is that it prevents Celebi from getting trapped by Choice Scarf-less Gothitelle and Wobbuffet, which can be important sometimes. Recover rounds off the set and enables Celebi to last throughout the match, as entry hazards and Life Orb recoil would take their toll pretty quickly on Celebi otherwise.Team Options & Additional Comments >>>
Nasty Plot Celebi can take advantage of the many free switches that it gets against Pokemon such as Keldeo, Politoed, Rotom-W, and Sheer Force Landorus by either setting up with Nasty Plot or hitting hard the switch-in with the good neutral coverage provided by three attacking moves. Unlike the specially defensive set, this set has a lot of offensive pressure, and unlike the offensive set, this set has better coverage, Speed, and power (after a Nasty Plot). Without Nasty Plot it wouldn't be able to sweep because Steel-types, such as Jirachi and Scizor, could ordinarily take a hit and then cripple back, however at +2 they are OHKOed by the appropriate coverage move. Giga Drain is a solid STAB move which also restores Celebi's health, which can extend its sweep further. Earth Power mainly takes care of Heatran and Jirachi, while having a chance to OHKO Scizor and Forretress with Stealth Rock after a boost. Hidden Power Fire is used to get past most Steel- and Grass-types such as Scizor, Ferrothorn, and Skarmory. Psychic is a strong STAB move that allows Celebi to hit Dragonite, Salamence, and Thundurus-T for neutral damage, while also OHKOing Gengar and Breloom, making it the best move for the last slot. Recover helps Celebi to survive even longer and possibly enables it to try to sweep more than once. Lastly, Hidden Power Ice is able to OHKO Dragonite and Salamence without a boost, while hitting Latios, Latias, Hydreigon, and Thundurus-T hard, but is usually outclassed by Psychic.Team Options & Additional Comments >>>
Celebi is a decent user of Choice Scarf due to its good Speed, bulk, and utility moves, namely U-turn and Trick. Leaf Storm is Celebi's main STAB move to dent Pokemon neutral or weak to it such as Keldeo, Terrakion, and Landorus. Hidden Power Ice is used mainly for the Dragon- and Flying-types that Celebi can outspeed and OHKO with it, while Hidden Power Fire deals with any Steel-type except Heatran. Earth Power handles Heatran, Lucario, Jirachi, Magnezone, and Infernape, and generally offers good neutral coverage with the other moves, while Psychic provides Celebi with a secondary STAB move that hits certain Pokemon such as Gengar and Breloom hard. Lasty, U-turn allows Celebi to scout while keeping momentum, while Trick cripples walls such as Blissey, Chansey, and Jirachi.Team Options & Additional Comments >>>
Grass Knot can be used instead of Giga Drain and Leaf Storm on the specially defensive and offensive sets respectively. Grass Knot hits most of the Pokemon in OU that are neutral to Grass moves for good damage, and doesn't drop your special attack, but it has pitiful power against Rotom-W. This is a big downfall, as countering Rotom-W is one of Celebi's main jobs. Grass Knot also hits Keldeo and Politoed for less damage than Giga Drain, limiting its usefulness even further. However, Grass Knot has some notable advantages, such as OHKOing Terrakion, and 2HKOing most Tyranitar, Gyarados, Jellicent, and Hippowdon after Stealth Rock, making Celebi more difficult to use as setup bait. Celebi can use a physical set with Swords Dance, but its physical movepool is limited, as the only viable physical moves it has are Seed Bomb, Zen Headbutt, U-turn, and Sucker Punch, making it struggle for coverage. As most Grass-types, Celebi can use a SubSeed set to annoy the opponent, but with the abundance of Pokemon that don't care about this strategy, such as Gliscor, Ferrothorn, and Scizor, this set will only waste Celebi's potential most of the time. Celebi has access to Calm Mind to take advantage of its already good special bulk and simultaneously raise its Special Attack, but many dominant Pokemon can OHKO Celebi even with a Calm Mind boost so it's usually not worth it. Celebi gets Reflect, Light Screen, and Healing Wish, all good qualities for a dual screen set. It also has the bulk, the resistances, and reliable recovery, enabling it to switch in multiple times and last throughout the game, to set up screens, and bring a teammate in safely and fully healed with Healing Wish. However, its 4x weakness to U-turn and its other weaknesses to common attacking types make it unappealing for this role, as it an be OHKOed by many Pokemon before it has the chance to set up. Finally, Trick Room can be used on any non-Choice Celebi to support a dedicated Trick Room team, but its high speed and the limited viability of such teams usually prevent this move from being more than a mediocre choice.
Checks and Counters
When looking to check or counter Celebi the first way that comes to mind is to capitalize on its many weaknesses. Pokemon that can OHKO it or severely dent it, and can switch in safely, are generally a very good way to deal with Celebi. Faster Pokemon with STAB super effective moves, such as Gengar, Volcarona, Choice Scarf Heracross, Abomasnow, and Ninetales, all destroy Celebi, but have to be wary of Thunder Wave, Psychic, Earth Power, and Hidden Power Fire in Abomasnow's case. Dragon-types, such as Kyurem, Kyurem-B, Salamence, Dragonite, Latios, and Hydreigon, handle Celebi pretty well, as long as they avoid Psychic, Thunder Wave, and U-turn on the switch. Lastly, Steel-types, such as Heatran, and Scizor, are proficient at handling Celebi, but have to beware of Earth Power, and Hidden Power Fire, respectively.
Then we have the Pokemon that usually wall Celebi and can't outright OHKO it, but can set-up on it, making it a liability for its team. Such Pokemon are Forretress, Venusaur, Skarmory, Ferrothorn, Latias, Lucario, Reuniclus, and Thundurus-T. Celebi can threaten all of them though, with the right move. Forretress, Skarmory, and Lucario fear Hidden Power Fire, Latias and Reuniclus are shut down by Perish Song, Latias and Lucario dislike Thunder Wave, Lucario and Thundurus-T are hit hard by Psychic, and Lucario hates Earth Power.
Another public enemy for Celebi are sun teams in general, which usually pack Fire-type moves on at least half of their members, as well as Fire-type Pokemon that can at worst 2HKO Celebi. Celebi also cannot hurt many of the Pokemon that are commonly found on sun teams such as Ninetales, Volcarona, Venusaur, and Victini.
Finally, there are the Pokemon that can revenge kill Celebi, but can't switch into it really well. Such Pokemon are U-turn Landorus, Terrakion with X-Scissor, Tyranitar with Pursuit, Mamoswine, Garchomp, and AcroBat Gliscor. Generally, any Pokemon that can outspeed Celebi and hit it with a Bug move, or a super effective STAB move is a good revenge killer.