Trasfomer animation using SHape keys

i have 6 set of dirrenet models, each a step for a ball transforming into a robot, Now as the models are different objects, can I use Them together IN shape keys to make a transforming animation?and how?

not with shape keys. shape keys have to work off a base mesh and you cant add/remove verts edges and faces from the mesh.

hmm so any ideas on how can i be able to achive sonemtihg that complex?

you may be able to do something with the shrink wrap modifier