[Pocket]

Writing this up separately from yee's Celebi revamp

[SET]
name: Baton Pass
move 1: Baton Pass
move 2: Calm Mind / Nasty Plot
move 3: Giga Drain
move 4: Substitute / Hidden Power Fire
item: Leftovers
nature: Calm
evs: 252 HP / 224 SpD / 32 Spe

[SET COMMENTS]
Calm Mind > Nasty Plot, since it is much easier to pass CM boosts than NP boosts.
101 HP Sub makes Chansey / Blissey set-up fodder and protects the CM recipient on the turn of Baton Pass
Substitute also blocks Dragon Tail - Careful Dragonite's Dragon Tail does not break Celebi's Substitute. After 3 CMs, not even Rain Tank's Hurricane would break Celebi's Substitute most of the time.
Specially Defensive spread makes setting up CMs on special sweepers much easier.
HP Fire can be used over Substitute to take out Skarmory before it can phaze Celebi's special attack boosts.
Many Rain Pokemon are set-up fodder for Celebi

[ADDITIONAL COMMENTS]
Thunder Wave gives it 25% fp chance of BP success against phazers, and it's a generally good utility move.
Earth Power to dispatch Heatran, which may phaze Celebi
84 SpA to OHKO specially defensive Heatran with a +2 Earth Power or a physically defensive Skarmory with a +2 HP Fire
72 Spe to beat Modest Heatran to the punch.
Swords Dance & Seed Bomb / Zen Headbutt to pass Atk boosts
Magic Coat / Espeon to cockblock phazers
Recover to keep it healthy
Rain support is nice to ensure Leftovers recovery and halving Fire moves. Obviously Celebi wouldn't use HP Fire in this case.
Special sweepers that benefits from a few SpA boosts, such as Thundurus-T, Keldeo, Starmie, Latios, Volcarona.
Wish Passer / Heal Wisher, such as Jirachi to keep Celebi healthy.
Teammates that can deal with Scizor, PSong Celebi, Volcarona, and Tornadus. Heatran is a good answer to many of them; Scizor can Pursuit-trap Celebi / Tornadus; Jirachi is the best answer to Tornadus; Gyarados checks Scizor & Volcarona.
NP + Tanga Berry