Vaporeon takes most special attacks with ease. If you really want a Wall Vaporeon, you can use this.
Vaporeon @ Leftovers
Ability: Water Absorb
180 HP 252 Def 76 SpDef
or if you want huge Wish heals, you can use 248 HP / 252 Def / 8 SpDef
It all depends whether you want to wall or heal.