I'd like to have DAH UHLTIMAET PRETENDAH!
First, you start with a Ultimate Class Transformers who change into a planet. The robot mode will be a little fat like Bulkhead or that red wrekcer guy.
Inside is a Voyager Class flying saucer à la Cosmos who change into another "fatty".
Inside is a Scout Class minivan who change into a "fatty"
Inside is a Minicon TV SET who look like a normal and fat human in bot mode.
The "planet" will be more like a space-station of some sort. Then our character goes to troll humanity by coming in like a 1950'S cliché. Then he start exploring in van mode. Then he infiltrate some military complex to spy, transforming into everything and everyone, with a volume and weigh equivalent to the average human.