Death Dose

Death Dose is a fictional drug and contains many ingredients that make it seem like a harmful drug. It is used against Charizard as seen in Smash Bros: Off The Screen S01E02.

Effects.
When Shulk visited Charizard in the hospital, he could see Charizard without his usual face, as it was a face of a Charizard skull. This was the only effect that was actually seen, but there was an actual explanation given in the episode that specific parts of the body starts to fade away and is replaced with the skeleton.

Cure.
In the episode, the cure is said to be the Master Core.