TormentTran is a great pokemon, but it really shines when paired with Toxic Spikes. For this reason, I think you should replace Celebi with a bulky Roserade set. Something like this.
Roserade @ Leftovers
Calm
EVs:252 HP, 56 Def, 80 SpD, 120 Spe
-Toxic Spikes
-Synthesis/Stun Spore
-HP Fire/Stun...