Kill all minions, then go to the central part of the arena and turn to the left. Build a huge rock with green handles from the debris, then lift it with the Thing and throw it at Green Goblin. Wait for him to go down, so you can easily make some boxing exercise.
In the second round you will be flooded by the ocean of the enemies - defeat them all, dodging Green Goblin's bombs in the same time. Wait for the stained-glass window on the right to become shattered, then build a huge swat from the debris. Now lift it with Invisible Woman - in this way you will force an enemy to fall on the ground, so you can hit him easily.
In the final round defeat all minions (as always), then approach to the shattered stained-glass window lying at the end of the arena. Build a Fantastic Four panel from the debris, then use it with Mr. Fantastic to catch Green Goblin for the last time. Strike him with the final blow, and the mission will be over.