How many X (size) creatures = Y (size)?

[Werefoowolf]

For 2 situations

1) I plan to give one of my players a custom version of the Consuming Creature template that lets his character consume (specifically oozes) to grow. I wonder how many oozes of a given size category she (his character) would have to consume in order to grow from Medium to Large. The same goes for Large to Huge, all the way up to gargantuan.

2) Odd circumstance, I want to give a dhampir party member an option to recruit vampires to his cause of going toe to toe with the final boss (a kaiju) that, upon the fight being triggered, his vampire loyalists would use Gaseous Form to meld together into ONE GIANT cloud of mist that a much larger vampire emerges from.

The ultimate showdown will likely be against a custom creature "Lunar Mogaru" my take on Pathfinder's equivalent of Space Godzilla, which should be CR 28+ so I'm trying to come up with any way to give the party access to cool kaiju concepts.

[Mavrickindigo]

Not exactly campaign setting questions, but I'll give it a shot

1.) The Bestiary describes size increases for creatures happening when their hit dice double. So a Medium sized creature with 1 HD would become large at 2HD, Huge at 4 HD, Gargantuan at 8 HD, and Colossal at 16. Of course, most creatures start with more than 1 HD at Medium size. Perhaps base your character's size on the size of a particular ooze and have the character grow at the points it would grow.

2.) I think at this point you could consider statting up a single vampire and giving it the troop subtype and all the things that go with that. That, or you could gather together enough vampires to make an Army (see Ultimate Campaign) and have it have mass combat against the Kaiju (you can see example of this in how Paizo statted the Tarrasque as an army)

That, or you could most likely fluff the numbers of the creature and create some kind of custom incorporeal undead monster with vampire abilities.

EDIT: Really, your second situation is dm fiat, more or less.