Why did Trayvon hide in the bushes? He clearly had a head start and would not have been caught even if Zimmerman had continued to follow him. Why would Zimmerman want to attack anyone? He had already called the police and was waiting for them to show up. Had Zimmerman seen Trayvon and Trayvon threatened him at all he would have pulled out his gun to defend himself and hold Trayvon until police arrived. Do you think Trayvon would have attacked Zimmerman if he saw a gun? He couldn't have been that stupid.
Therefore the ONLY reasonable scenario is that Trayvon hid behind a bush and jumped Zimmerman, punched him in the nose, put him on the ground, got on top of him and started beating his head into the pavement. That is the only reasonable scenario that makes any sense. Any other version is not only speculation but speculation that doesn't fit the evidence or logic.