So I would like to make this cake for a cousin's birthday this weekend and have a question about sizing.

Would the character be made using 6" and the base cake be 8"? Also how high should I aim for for Baymax? I'm thinking 3x2" high cakes plus the top curved piece of the body and then a dummy head? 

https://s-media-cache-ak0.pinimg.com/736x/8a/f0/e1/8af0e1fb748047a1ebd6b0cf80853cef.jpg

Also any idea of the name of the blue thats used? 

I don't know what was used but I would use the 8 inch base and then 6x3 or 6x2 inch layers with half a ball pan on top. I would sculpt the head from two layers of a 4 inch cake.  I actually have to make the figure for July and have been planning a trial run soon.  Interested to see responses by others who may have made similar cakes.I made a minion cake and other than the head on top, the body shape is similar.

Maybe the a doll cake mold?

GoWildCakes that sounds like a good idea too.