Jolly won't be doing Dnite any good since your SpA is reduced. I'd still suggest Multiscale over Inner Focus since you'll die from an Ice Shard from Mamoswine, which in my opinion is worse than getting flinched. Also, it will help you against threats you can't OHKO but can OHKO you back with an Ice-type attack. If you still want to use Inner Focus, replace Waterfall with Superpower. Yea sure they have the same power under the rain but Superpower hits a lot more Pokemon than Waterfall does, especially Ferrothorn which can take any move on your set. Regardless of the abilities, replace your nature with Hasty to keep up speed while not reducing your attacking powers.
A few more minor changes. On Volcarona, replace Fiery Dance with Fire Blast because it has a very good chance of killing Ferrothorn under the rain even without a boost but you'll need entry hazard damage. On Alakazam, replace Energy Ball with Hidden Power Fire to hit Scizor harder than any other move on your set. And use Focus Sash. Even without Life Orb boost, Alakazam still hits very hard with 135 Special attack. Focus Sash will save your ass especially against Scizor thinking that you'll switch and lock itself into Pursuit which kills Zam whether it stays in or not.
Hope I helped and Gluck
A few more minor changes. On Volcarona, replace Fiery Dance with Fire Blast because it has a very good chance of killing Ferrothorn under the rain even without a boost but you'll need entry hazard damage. On Alakazam, replace Energy Ball with Hidden Power Fire to hit Scizor harder than any other move on your set. And use Focus Sash. Even without Life Orb boost, Alakazam still hits very hard with 135 Special attack. Focus Sash will save your ass especially against Scizor thinking that you'll switch and lock itself into Pursuit which kills Zam whether it stays in or not.
Hope I helped and Gluck