Captain Deadbeard hits pretty hard and can take a chunk out of the plant hero's health, or heavily damage and destroy a majority of plants in one attack, most likely weakened by the explosion from Barrel of Deadbeards. However, if Captain Deadbeard is threatened by a plant that can destroy him, making him do a bonus attack is helpful since he has high strength, though only Professor Brainstorm can normally do this. Since Captain Deadbeard is a pirate zombie, Impfinity can boost him with Swashbuckler Zombie as long as he does damage to the plant hero, which Impfinity can easily do by moving Captain Deadbeard with Smoke Bomb or by having Captain Flameface on the field.
Against[]
Captain Deadbeard may look like a threat, but he is not as devastating as you think; he hits hard, but there are many cards that can destroy him in one hit, like Fire Peashooter . If Captain Deadbeard is made at the end of the turn, play said cards to block and destroy him. If he is made in the Plants Play phase, they will still survive Barrel of Deadbeards' ability and destroy Captain Deadbeard unless it is a Wild Berry or a Peashooter + Torchwood combo.
But the best counter is not to touch any Barrels of Deadbeards, as the main way of having Captain Deadbeard out on the field is by destroying said zombie.