I mentioned Thunder because the 3 main reasons to use it over Psyshic/Psyshock were Tornadus, Politoed, and Sableye. Tyranitar is irrelevant as you can just Baton Pass to Vaporeon/Mawile and setup. Two of them are always found under rain, and of 'course the extra power helps, as it kills them faster, giving them less chances to disrupt your chain. Thunder even helps against Sableye with its paralyzing chance and the potential to 2HKO at +1, something that Thunderbolt can't do.
And how are you gonna often have SpA boosts when those Pokemon lurk in the corner and pressure your chain so much (Politoed, Sableye, and Tornadus)?
Thunder deals with the most common worries of Baton Pass chains (Tornadus and Toed, which are always under rain) better than Tbolt so please add it to the AC.
When you have a lot of attacking boosts, you don't need power. You need something that hits all of the relevant targets consistently. The reason not to use psychic is that it does no damage to tyranitar and sableye. Thunderbolt is the next most powerful option, and the super effective hits it gives are a nice bonus. The power of Thunder vs Politoed and Tornadus is totally unnecessary, and certainly not worth the inconsistency against everything else.
I am happy to mention Thunder, but only to explain why you shouldn't use it. Bearing in mind that Thunderbolt is only in AC anyway, this seems a bit too much detail to me.