In the Portnoy kit (he's pretty kick-ass, by the way) you can see that it's two kits in one - notice there are two thrones. He plays one side of it or the other. Similar to Tony Verderosa's hybrid kit (that he played in the Kit-Kat commercials around 2001) If you want a staggeringly huge kit, you have to go with Bozzio:
And yes, he uses it all at once - he sounds like an orchestra, each of his limbs being a different group of instruments.
On his website there is a list of instruments in his kit - you actually can't squeeze all of it into one photo.