I don't need to tell you it's a well built stall team so I won't bother ;)
I'm just wondering, have you ever considered the odd combination of Dark Pulse + HP Fire on Spiritomb. Even though I know this team heyday was significantly prior to platinum, SD Heracross (and now SD Scizor with platinum) could be a bit problematic. HP Fire also removes any Forretress from the picture that like to get cute and lay down some Spikes of there own. Still also deals with Lucario etc. Although, Heatran unfortunately is walls it but Blissey + Tentacruel + (if you are really really desperate) Hippowdon can usually handle it anyway. I suppose it helps with CB Tyranitar, HP Fighting that is, since CB Pursuit / Crunch still hurts even though it's not weak to it and you don't want to lose your anti-spinner. Ugh, tough decisions :[. Just wondering if you've ever thought about it. I'd probably end up using SBall+HP Fighting myself, but just throwing the other idea out there.
Just a thought. Probably too bizarre lol.
Edit: Personally, I'd run Reflect on Celebi over U-turn but to each their own (I get why you use U-turn I've just always found that I like Reflect, both are good options though).
Edit 2 @ below post (Conan Edogawa415): Nobody runs ThunderPunch on MixApe. I can always come up with a hypothetical Pokemon that can beat any team; but in reality it just doesn't exist in practice so it's largely a moot, purely academic point. Besides that, even a maximum Attack Hasty Life Orb ThunderPunch doesn't OHKO Tentacruel (who is arguably the best counter to any MixApe). A Life Orb Close Combat barely even scratches Hippowdon. For Fire Blast / Hidden Power Ice to be effective against Hippowdon you can't use maximum Attack either making the threat of ThunderPunch significantly reduced against Tentacruel. The only way that set really hurts this team is if that Infernape is running Infernape @ Life Orb, Hasty, 252 Atk / 252 SpA / 252 Spe.