Personally, I'm getting a bit tired of all the leak threads and want the god o'l speculation back. So I've decided to revive this thread again. Hope you enjoy my new idea!
After playing through and beating Jak and Daxter: The Precursor Legacy, (Great game by the way! I'm really looking forward to playing Jak 2 and 3.) I think the Precursor Robot driven by Gol and Maia would be absolute perfect candidates!
The battle would take place over a Dark Eco silo like in the first game. As you fight the machine, parts of the ground will break way to hazardous Dark Eco leaks that may cause you harm if you make contact with them. Gol and Maia will be able shoot laser beams at you and throw bombs. Also, they can summon a floating mine-esque device that will self destruct after an amount of time. They also have the ability to shoot Green Eco into the Dark Eco, resulting in Lurkers coming out which will be enemies during the fight you can easily dispose of. The goal to wining this fight is basically trying to hit with long range weapons that spawn the field like potential Red Eco that can shoot fireballs and attack them. Once they're damaged enough, they'll land on the ground to recover and you could beat the robot up. Soon, victory will be yours!
Here's a video showing the whole process:
By the way, just call me Count for short.