I would like to see insecticons, i think there's a cool way to make them both giant and life size insect like. Made the robot transform in giant insect, and make them composed of mini mecha insects, who acts like nanobots. So each insecticon could turn into a swarm of lifesize insects, AND in giant insect. The swarm could be a way to better assimilate/eat materials/energy, and for mimetic/spying purpose.
I also pretend Soundwave, and they could explain the mass change with some sort of mass driver, or energy/mass converter, after all he was the one who made energon cubes, what if he can convert his own mass in energy? In taper recorder/boom box/sound device he coul be equipped with some sort of extremely high capacity "battery". Or he could emit a large quantity of energy to change mass, and suck it back from environment(movie hulk like) to grow back, he could be cool to see the tape recorder absorb every electricity/heat in a building to regain back his size. They could explain in several ways, even without calling for pocket dimensions. The size change could even be used as a a cool way to make Soundwave have multiple alternate forms, transforming in different sound related things at different sizes, to better blend in...
Even dinobots could be easily done. Just make them transform in dinosaurs AND some modern things. Like, they came to earth in the prehistoric age, reconfigured themselves to appear as dinosaurs, then they were hibernated, and in present time they add another alternate mode, maybe they can't discard the other alt mode because they are damaged or are "old models". So they could turn in dinosaurs only to fight better in melee etc...
