During Chapter X (10), you'll be playing as Megatron. This could be some what of a challenge getting 5 Autobots together in the same spot. The best spot I found is to wait to you get to the end of the chapter. When Shockwave is hacking a command center. Pick up a Diffraction Barrier behind the command center. Then go to the right side, and hover up to the high beams. Stand and wait till the enemies start to come out from in front of you. Throw down your Diffraction Barrier, so you don't take damage. Wait till a group of 5 Autobots, press to hover and then again to preform a hover slam.
Here is a great video by NeedToAchieve showing you a perfect area to obtain this.