Celebi

Natural Cure
Cures status on switching out.
Type Tier
Psychic / Grass OU
Statistics
Min- Min Max Max+
HP
100
- 341 404 -
Atk
100
212 236 299 328
Def
100
212 236 299 328
SpA
100
212 236 299 328
SpD
100
212 236 299 328
Spe
100
212 236 299 328
Name Item Nature

Calm Mind Passer

Leftovers Timid
Moveset EVs
~ Calm Mind
~ Baton Pass
~ Psychic / Hidden Power Grass
~ Recover / Substitute
252 HP / 80 Def / 176 Spe

The standard. Calm Mind up against enemies like Zapdos and Blissey, and then Baton Pass to your own special attacker, such as Zapdos, Tyranitar, or the like. Psychic or Hidden Power Grass are to allow it to do some damage of its own. Psychic stops Heracross and Zapdos better, whereas Hidden Power Grass will OHKO Dugtrio and screw up Tyranitar that think you are Dragon Dance bait. Substitute can be used to block status and critical hits as you Calm Mind up.

Name Item Nature

Heal Bell

Leftovers Bold
Moveset EVs
~ Psychic
~ Leech Seed
~ Heal Bell
~ Recover
252 HP / 220 Def / 36 Spe

A decent Heal Beller, an awesome Swampert counter, and an overall annoying Pokémon. You can send Celebi against nearly anything because even if it's super effective and non-STAB it won't really do that much, the exception being Hidden Power Bug, which will almost always 2HKO Celebi.

Name Item Nature

Perish Song

Leftovers Impish
Moveset EVs
~ Hidden Power Grass / Reflect / Protect
~ Heal Bell / Reflect / Protect
~ Perish Song
~ Recover
252 HP / 144 Def / 82 SpD / 32 Spe

You can't use this on its own, but with Umbreon support, even heavy attackers have a hard time getting past a Perish Song. Umbreon has a Mean Look / Baton Pass move combo to pass to the Celebi, which in turn uses Perish Song to finish the enemy off. It is a good combo because Celebi, as stated above, has incredible defenses. Protect can help stall vs. some Pokémon as you wait for Perish Song's count to run out. Reflect is used mostly because Celebi doesn't have much else to do. Reflect is generally superior to Protect, because Celebi has the defenses to Recover off most special damage, and if you're just stuck in a Recover loop vs. a move like Metagross Meteor Mash that 2HKOs, you're just begging for an Attack up / critical hit. Reflect maintains its defensive boost through critical hits, however.

Name Item Nature

Swords Dancer

Leftovers Jolly
Moveset EVs
~ Swords Dance
~ Baton Pass
~ Hidden Power Fighting / Shadow Ball
~ Recover
252 HP / 80 Atk / 176 Spe

Physical Celebi, while not as effective as the others, is a decent Tyranitar counter and can really surprise some stuff. You won't be hitting Skarmory that hard, and having a weakness to Flying is never a plus. You'll have a hard time Baton Passing with Skarmory around. Not the best set but it can work and shows off Celebi's variety. This messes up Snorlax and Houndoom who think they can counter Celebi.

Other Options

Toxic is for stall themes and Safeguard is for stopping status but in general Substitute is recommended over it, and Celebi already has Natural Cure. It can use Light Screen for pseudo-passing, but why not just pass a Calm Mind? Giga Drain can be used over Hidden Power Grass, but the lower damage and PP will really hurt a stall-oriented Pokémon like Celebi.

EVs

For the Calm Mind versions, you want 244, 270, 299, or 308 Speed, depending on what you want to beat. 244 guarantees you beat Tyranitar with minimal investment, and also blocks Modest Magneton and Adamant Breloom. 270 Speed is faster than Adamant Heracross. 299 Speed is faster than Jolly Heracross, ties at worst with most Salamence, and is faster than a host of other Pokémon. 308 requires a Speed boosting nature, but outruns all base 90 Pokémon. Defense is also nice for the Calm Minder. For all the Substituters, you will need 404 HP.

Opinion

Celebi is a stalling machine, but the Perish Song Celebi can also act as anti-stall with Umbreon Mean Look passing. The Baton Pass set can do serious damage to Skarmory with STAB, Calm Mind boosted Psychic, and Blissey can't stop special attacking sets thanks to the chance of a special fall, and Celebi's 404 HP with Recover and Natural Cure as well as Leech Seed. Celebi can take on Electrics to a great extent thanks to resisting their main form of attack, and since most Electrics carry Hidden Power Grass for Swampert, you have nothing to worry about from that corner, either. Not to mention Celebi can contribute to a Baton Pass chain with Calm Mind, Swords Dance and high HP Substitutes. Celebi's power is such that many respected battlers have attempted to get Celebi banned multiple times. Celebi was even banned from the Smogon Tour for a while.

Counters

Shiftry and Cacturne can come in on Celebi and block it all the time (except for the rare Hidden Power Fire), but they're kind of helpless if it's a Baton Passing Celebi, unless they're carrying Hidden Power Bug. Houndoom can easily come in on about anything except Leech Seed or Calm Mind and will hurt a switching Celebi with Pursuit, or just Fire Blast it back to hell if it stays in. Tyranitar hates Leech Seed but anything else is welcome, especially if Tyranitar has Taunt, though Celebi will hate Crunch (with some critical hit or Special Defense drop luck) or Dragon Danced Rock Slides either way, unless Celebi has Hidden Power Grass.

Skarmory resists Psychic so it's a good choice to counter Baton Passing Celebi, and it scares Celebi in general with Spikes and Drill Peck / Hidden Power Flying, however it doesn't like to get Leech Seeded and Psychics will start to hurt after a while, especially with a Calm Mind to back them up. Predict accordingly. Choice Band Salamence OHKOs some Celebi with Hidden Power Flying and is usually faster, but also has to watch out for Psychics on the switch and also those 300 def Celebi.

Suicune and Dusclops can abuse Pressure to stall Celebi out of Leech Seed or Psychic, but they cannot really hurt it much. Suicune can Roar Celebi out, preventing it from Baton Passing that Calm Mind, and also can Roar out Perish Song Celebi, so it's a surefire counter for any set. Even Hidden Power Grass doesn't do that much, and Giga Drain's 8 PP max will run out real fast. Dusclops 3HKOs with Shadow Ball. Articuno easily comes in on whatever Celebi is pulling (except Ancientpower, which you'll likely never see), kills Leech Seed and Psychic PP with Pressure and Roars away stat boosters. Its 125 Special Defense helps a lot, as does STAB Ice Beam. Regice counters Celebi pretty well too as it has insane Special Defense and a powerful STAB Ice Beam. Some Regice carry Psych Up, so beware if you're thinking of boosting.

Espeon, Alakazam, Mr. Mime and an opposing Celebi also work because they resist Psychic, but once again they won't like Leech Seed and with the exception of Encore, Taunt or Trick from Alakazam and Mr. Mime, they cannot really stop the Baton Pass.