To defeat Jazz with Megatron, climb the building behind you and attack all the turrets without destroying them. When all five turrets are decently damaged, go to one of the corners and attack the furthest one. After doing this, Jazz will send Autobots to attack you. Ignore them and just go to the next turret and destroy it. Continue doing this until none remain. After finishing this, a cinematic with Megatron chasing Jazz will play. When the battle starts, attack Jazz with your heavy weapon, which will be difficult because Jazz is always moving. However, he will receive a lot of damage. Also, if possible, do not go toward Jazz because he will simply jump away. If your health gets too low, find the entrance to the Sector 7 underground base. If you see it, barely go into it then start running and transform. Use the afterburner or Jazz will shoot you. If you manage to get to the bottom, destroy objects for health. Once you have full health, go back out and attack Jazz again.