The standard spread seems fine to me, except you have to remove the speed and change the nature so you are as slow as possible. 252 HP / 156 Def / 84 SpD / 16 Spe Bold becomes 248 HP / 152 Def / 108 SpD Relaxed with 0 Spe IVs then. The SpD EVs allow you to avoid the 2HKO from Keldeo's Specs Icy Wind after Stealth Rock 98,8% of the time.
To be honest I'm also not convinced of Trick Room Celebi. Celebi is a great teammate to Mega Camerupt, but I think Calm Mind + Baton Pass is a better form of Support than Trick Room simply because Trick Room is kinda underwhelming in general.