Chinchou
So, if you don't use Chinchou there, you become weak to stuff like Zebstrika with Gabite as your Volt Switch stop, but this team uses RestTalk Machoke as a blanket check for a lot of stuff (Zeb included). With 3 resists to Rock, that last slot can actually be open to more offensive Pokemon weak to SR to give you another Machoke check, given Swanna is acting as removal here.