I'm actually not sure about this but the description of Helping Hand is;
Helping Hand is an increased priority move that will raise the base power of the adjacent ally's move in a Double Battle and Triple Battle by 50%. It will fail if used in a Single Battle. It will also fail if the partner has already used Helping Hand that round in Double Battles but will stack in Triple Battles.
The only stated conditions of failure are in a single battle or attempting to stack on the same Pokemon in a doubles battle.
This means in theory it would be fine if Cherrim used helping hand and then fainted/statused it would still work as long as Typhlosion didn't get killed. Since Cherrim used it before.