setup sweepers such as thunderus and volcarona seem a big threat u could fix this by using a sdef heatran over ur current set
(Heatran) (M) @ leftovers
Trait: Flash Fire
EVs: 248 HP / 252 SDef / 8 Spd
Calm Nature (+SDef, -Atk)
- Lava Plume
- Roar
- Protect
- toxic