The monster attempts to grab Wonder Girl, since she's the most obvious threat.

Aqualad and Robin pull out their weapons and prepare to attack it; Kid Flash notices the threat and skids to a halt so he can come back to help. 

She ducks inside his grasping reach and slams as much force into his solar plexus as she can manage on short notice. 

Aqualad attempts to hit the monster with a water whip. It lets the whip wrap around its arm, then grabs it and uses it to pull Aqualad in so it can punch him. 

Meanwhile, Kid Flash blurs past and tries to punch it.

He stumbles to a halt a few yards away, wincing and shaking his hand.

Fortissima telekinetically throws some rubble at it. 

--Is there anything sharp around?

Chunks of rubble seem to do some damage to the monster! It roars, and looks around for the person who threw them, but hasn't yet made the connection with Fortissima. 

There are more broken bits of concrete lying around; one of them might be sharp enough to do some damage. Other than that, this area seems empty of everything but the bunch of kids fighting a monster. It seems to be some kind of garage or loading area, but there's nothing waiting to be loaded right now. 

She grabs the sharpest piece of concrete she can find and tries to sneak up behind the monster while it's distracted by being pelted with rubble.