Use a Bold nature on Chansey and this EV spread: 252 HP/252 Def/4 SDef.
DynamicPunch is rather weak on something like Dusclops. Starmie might be a better Gravity user because it can actually hit back:
EVs: 4 HP/252 SAtk/252 Spe
Item: Leftovers/Life Orb
Ability: Natural Cure
Use Toxic, Ice Beam or Blizzard in your last slot on Vaporeon.