I suggest changing something to a scarfer. That Terrakion could function well with a Choice Scarf. Also since, you're running bulky spinner variant on Starmie, I suggest recover for more longevity. Don't know what you would replace it with though.
FC: 1650-1657-1108 | Pokemon X IGN: Justin Call me Xat :D
As far as a competitive team, Nintendo tourneys limit only one use of held items per team (i.e. only one Leftovers, you currently have 3 ) Also, your type coverage is a bit lacking. I also like Moxie on Gyarados more than Intimidate.