Fight Club: Swamp Thing VS Man Thing

SWAMP THING

Strengths: He's made of pure vegetation, so he can't be killed by conventional means (shooting, stabbing, beating etc). He's super strong. He's a mean bastard who's out for revenge (both for the people who "killed" his human form and for people who hurt Mother Nature). His consciousness can switch to any mass of plants, at will (so if his body gets destroyed, he can simply move on).

Weaknesses: He's a moody bastard so when he gets depressed, he just stops moving and lays there.

MAN THING 

Strengths: He's strong. He is almost invulnerable to harm. He can turn himself into ooze. He has psychic and mystical powers.

Weaknesses: He grows weak if he leaves the swamp. He's somehow associated with Howard the Duck.