Each Hero starts the game with one random superpower and recieves another each time a Super-Block is activated (you get three Super-Blocks a match). Below is a list of the various superpowers and what they are capable of doing.
Plant Superpowers
Green Shadow - Precision Blast:
Attack for 5 damage in the middle lane.
Solar Flare - Sunburn:
Do 2 damage. You get +1 sun for the rest of the game.
Wall-Knight - Uncrackable:
Your Hero can't be hurt this turn. Draw a card.
Chompzilla - Devour:
Destroy a Zombie with the lowest Health.
Spudow - Tater Toss:
Make a 1 Health Hothead that says 'Team-Up. When destroyed: Do 6 damage to a Zombie here'.
Citron - Peel Shield:
Plants can’t be hurt this turn. Draw a card.
Grass Knuckles - Power Pummel:
Attack for 2 damage in each Ground lane.
Nightcap - Mush-Boom:
Make a 1/1 Poison Mushroom with Anti-Hero 2. Do 2 damage to a Zombie there.
Rose - Goatify:
Transform a Zombie with the highest Attack into a 1/1 Goat.
Zombie Superpowers
Super Brainz - Carried Away:
Move a Zombie. Then it does a Bonus Attack.
The Smash - Slammin' Smackdown:
Destroy a Plant with 4 Attack or less.
Impfinity - Triple Threat:
Make two 1/1 Impfinity Clones with Amphibious in random lanes.
Rustbolt - Shrink Ray:
A Plant gets -3 Attack. Draw a card.
Electric Boogaloo - Stayin' Alive:
Do 3 damage to a Plant. Heal your Hero for 3.
Brain Freeze - Frozen Tundra:
Freeze ALL Plants on the Ground.
Professor Brainstorm - Eureka:
Add three random Cards from the entire game to your hand.
Immorticia - Witch's Familiar:
Make a 2/1 Zom-Bats that says 'When this hurts a Plant: Draw a card.'
Z-Mech - Missile Madness:
Attack for 2 damage in three random lanes.
Neptuna - Octo-Pult:
Make a 3/2 Octo-Pet with Amphibious.