Who haven't defeated the JLA...not impressed. Titus defeated them, Konvikt worked them, Despero defeated them, Doomsday defeated them, Shaggyman defeated them, the General defeated them, if Hulk was in DC, he would defeat them. They suffer badly from the ninjas law and using a battle against them as some type of evidence isnt beneficial at all. Hulk would beat most if not all of the people mentioned above and again, they defeated the JLA.
Back on topic...Hulk is stronger, more durable, smarter, and a much better fighter. Hulk kills Grundy. Grundy would have been one of those peeps in the dark dimension punching at Hulk to no avail and melting just like everyone else did from a backlash of Hulks power.
Hulk 10/10