I've been meaning to get around to posting this thread, but have been busy with analyses and schoolwork. Celebi is an interesting dude in Ubers, and has some worthwhile sets. I've tested several with mixed, but overall positive results. And as Theorymon is apt to point out, Celebi cannot be completely divined by numerical analysis, it has to be experienced.
I will not be posting Celebi sets that are performed better by other Pokemon. These include things like the SubSeeder, which is outclassed by Jumpluff and Skymin because Celebi's bulk over them is negligible and easily compensated by the superior speed and movepool of the other two. Choice Celebi sets are outclassed readily by things like Mewtwo and Palkia.
Celebi @ Leftovers / Lum Berry
Ability: Natural Cure
EVs: 252 HP/128 Def/128 SDef
Calm nature (+SDef, -Atk)
- Stealth Rock
- Thunder Wave
- Grass Knot
- Recover / U-turn
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This plays similarly to the Groudon support lead. The idea is to use Thunder Wave and set up Stealth Rock. Celebi has enough bulk to live through attacks like Ice Beams from Mewtwo and Kyogre and Fire Punches from Groudon, so you can reliably get up Stealth Rock, although paralysis is preferred. The last move is up to you: Recover can help you gain health and stall for parahax, while U-turn makes sure that Wobbuffet doesn't anally rape you. This set works well on any Ubers team that isn't a stall team.
Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP/6 Def/252 SDef
Calm nature (+SDef, -Atk)
- Perish Song
- Recover
- U-turn
- Grass Knot / Leech Seed
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This is a stall team's answer to things like BU Dialga, Cro Kyogre, and assorted Sleep Talkers, although I found such duties kind of redundant on mine. But that's probably because I like using CM Latias. Either way, don't even think of replacing U-turn, if only because of Wobbuffet being able to lock you in and murder you if you do replace it. If you want to use this set, try it on a Modern Stall team like Jibaku's, replacing Kyogre with it. I don't have the highest opinion of this set, but I can see why people would like it.
Celebi @ Leftovers
Ability: Natural Cure
EVs: 252 HP/80 SDef/176 Spd
Timid nature (+Spd, -Atk)
- Calm Mind
- Grass Knot
- Recover
- Baton Pass
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Things like Palkia, Dialga, and pals don't get Calm Mind, so they can benefit from being passed a few. Also, another one of your Pokemon, even if it gets Calm Mind, can benefit from forgoing the move in exchange for coverage. You may want to try this with Wobbuffet or Screen support, but otherwise you can setup on stuff like Kyogre stuck in Thunder/Surf or against the new Groudons. Since you outspeed Kyogre and resist Water and Electric, you can counter it provided you avoid an Ice Beam.
Celebi @ Leftovers
Ability: Natural Cure
EVs: Undetermined
Timid nature (+Spd, -Atk)
- Swords Dance
- Seed Bomb
- Recover / Leech Seed / Substitute
- Baton Pass
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Even fewer Ubers get Swords Dance, and it is easy to sweep on the physical side against many Ubers, since there is no equivalent of Blissey. If you can pass to something like Dialga, Palkia, Mewtwo, or by some miracle Deoxys-A (accomplished via Celebi taking a hit likely buffered by screens and then passing), your opponent will probably shit himself. There isn't much documentation on this set, but you probably want to use Wobbuffet or Screens to help you pass.
Anything I missed? I know several of you have opinions on Celebi probably more educated than mine, so I would like to hear them!