Just looking at the build it looks like it's very reliant on Garchomp to consistently deal with Ferrothorn, who can come in on 4 members of the team, although it needs to be careful coming in on Politoed due to Scald potentially burning and being able to fire off T-wave mostly risk-free or being able to dent Garchomp with either Gyro Ball or Power Whip (the former almost always 2HKOs after rocks whereas T-wave+Power Whip really gives this team a headache in general) or if it comes in expecting T-wave. That said I think that if you can keep the rain up consistently it will eventually be overwhelmed, although I think that carrying Surf>Scald on Kingdra makes this unnecesssarily difficult in general due to it not being able to increase the pressure on Ferrothorn with a burn, and I think that the headache that it causes if it can spread T-wave and seeds around enough may often be enough for it's teammates to then be able to finish it off once it's checked them for long enough. If anyone wants to partner up with me later to confirm or debunk this (I can't now but I'll probably be available to test at around 18:30 or 19:00 BST) feel free to hmu in PM or VM.