Here's an idea I recently came up with. Before the fighting begins, Chomper suggests talking to Screech and Thud about letting Pangaea free. The negotiators for the rescue party will be Chomper, Ruby, Chronicler, and Claw (Myrkin), with Chomper being the translator. I haven't thought about how the talks will fail, but they will fail. (They have to, otherwise we won't get to the fight scene.)
Sounds good to me!

There's a convenient reason for the negotiations to fail as well: Screech holds a grudge against Pangaea for attacking and humiliating him during the sharpteeth's first attack on the valley; even if Chomper managed to convince Red Claw that Amy is gone and that he has no reason to keep Pangaea captive, Screech would refuse to release him. (The rest of the group would have to strike quickly afterwards, though, because Screech would have no reason not to begin exacting his revenge on Pangaea either).
Since I plan on getting injured, that could cause me to opt out of the fight or something, or I get knocked out. Otherwise, we could have more fast biters come by to have something for all our characters to fight.
At first I was unsure about the idea of bringing more fast biters in, but it occurred to me that Red Claw would be expecting a rather large force of leafeaters to arrive, and would need a means of distracting them all if he were to get a shot at capturing Amy. How about I have Thud round up an unspecified number of other fast biters (using the promise of a large meal to motivate them to cooperate), who attack the group when the conflict begins, immediately following the failed negotiation attempt?
I had an additional idea that I might as well share: perhaps Screech could be the one who injures Rob. Rob could confront him with not only the intent of furthering the group's mission, but with the reasoning that Screech would be a somewhat safer opponent for him to confront, given that he's holding Pangaea and thus can't use his hands to fight. However, Screech manages to give Rob a shallow wound with one of his sickle claws, thus putting him out of commission. Unfortunately for Screech, this also punches Anna's berserk button; seeing Rob get injured, she whales on Screech and takes him out, freeing Pangaea in the process. I dunno if it sounds silly or anything, but what do you think of that?
Anyone else have any special things they'd like to do?
EDIT: I'm still not sure what role the gang could play in the rescue.