Here is the moveset for in game: Shiinotic Nature: Should be Timid or Modest but I'm too lazy to find one LOL Hold: Leftovers or Big Root Ability: Effect Spore - Giga Drain - Spore - Moonblast - Dream Eater
Leftovers is generally the best item. In this case, it's better than big root because big roots are useful only when you're using a draining move on a low special defense opponent.