What about Protect? I have used a Protect+X-Scissor Parasect with Insect Plate over Leftovers and it allows Parasect do deal over 52% to Wobbafett switch-ins. (Which can cause hefty damage).
This is also without an Adament nature. I opted for a +Special Defense - Special Attack nature (forgot the name).
Point is, between attacks, (before and after Protect), Parasect can heal 25% before taking its next attack, and all the while deal more damage thanks to Insect Plate, invest more EVs into its Defenses, and use a Defensive Nature all the while dealing and healing more damage than on the suggested set.
The only trouble is deciding what to replace Parasect's 4 move: (obviously keeping Spore, X-Scissor, and adding in Protect, and deciding between Stun Spore, Aromatherapy, and Light Screen).
Perhaps have a Blissey/Celebi with Heal bell, or simply rely on Kyogre's Thunder for Paralysis instead of Aromatherapy/Stun Spore, or a Light Screen Forretress?
Heck you could even keep Parasect's Leftovers and use Protect to heal 36% between turns (turning many 2hkos into 3hkos), as well as scouting in general. Shouldn't Protect at least be mentioned in other options?