[Joeyboy]

Really great team man! The type synergy is really great, and I really like that your team does a good job paving a way for a Reuniclus sweep (I too have a team that does this, though with a different approach :)

So the first threat that comes to mind is Sub CM Jirachi. While Gastrodon walls any standard Water Pulse/Thunder Variant, all it takes is a Psyshock/Thunder(more effective imo anyway) variant to do a lot of damage to your team. My first recommendation is changing Earth Power for Earthquake on Gastrodon. This makes a world of difference against Jirachi as it can hit the weaker physical side. There are practically no downsides to this as you've not invested in any SpAtk and Earthquake has a higher base power.

A small change I would like to suggest is running Quick Attack over Superpower rather than over Pursuit, so that Scizor is running BP/U-Turn/Pursuit/Quick Attack. Superpower is really used to hit, specifically, Heatrans and Ferrothorns on the switch-in. Your team doesn't really mind either of those pokemon; Ferrothorn is perfect set-up bait for Reuniclus and Heatran can be dealt with by Latios, your own Heatran, or even revenge killed by Terrakion. Pursuit on the other hand can be used to reliably trap and kill some really problematic pokes, specifically Latios and Latias. Your only resist(Heatran) has no bulk invested and Gastro can't take repeated Draco Meteors. Now while a Choice-locked Pursuit can be easy to set-up on I believe your team will be able to check any of those threats(example SD Lucario can't reliably sweep with your CS Terrakion in the wings). Quick Attack I believe will also be more helpful than Superpower because it turns Scizor into an even better Revenge-killer for numerous other threats.

Another thing of note this that your main rain counter(Gastrodon) can be very easily lured and killed by those Random HP Grass 'mons on Offensive Rain teams. Really thats just something to look out for, but if you keep having trouble with it let me know :)

Hope you try these suggestions out, lemme know how they go!

Good Luck!