Darkrai...Invincible?

[Machampion]

I am a level 52 Charmander (Hero) with a level 53 Pikachu (Partner) and Cresselia keeps dying! I can stay alive just fine and.. so can Pikachu.. But Cresselia IS TERRIBLE, She keeps dying and dying.. I even had 6 reviver seeds, All gone.. All wasted.. I am playing PMD:EOD..

[Chromatic Alchemist]

Oh believe me, I had the same problem on Sky. I had a perfect Riolu that killed Darkrai ever so fast, and Eevee held its own or ran, either of which I preferred. Cresselia, however, was the pain in my ass.

All I can say is, while searching the Deep Dark Crater, scour the floor for all items possible. I have found numerous Reviver Seeds that can help your cause. Other useful items are Quick Seeds or Hunger Seeds (for Darkrai).