Shame Phione is underestimated. I like using it as a set-up tank.
Phione @ Damp Rock
EVs: 252 HP / 128 Def / 124 SDef
Calm Nature (+SDef, -Atk)
- Ice Beam / Protect
- Rain Dance
Rest puts in instant HP. Toxic walls, and puts pressure on the opponent if they are unable to break Phione with ease. Ice Beam / Protect is a taunt blocker and STAB or stall. Rain Dance adds rain support. Try dis with Kingdra. Excellent core.
Damp Rock lengthens Rain time for Rest. Hydration is excellent and required. EVs throw in awesome bulk. Nature is pretty obvious.