For this tutorial, i will be speaking of theoretical people via letter variables (X is a person and Y is a person, etc etc.)
We will be assuming a 12-player session because it is the largest we have canonically seen. Our character list is now X , Y , Z , A , B , C , D , E , F , G , H and I
Prototype X and I into D's kernel.
Prototype Y and H into E's kernel.
Prototype Z and G into F's kernel.
Prototype A and F into G's kernel.
Prototype B and G into H's kernel.
Prototype C into D into I's kernel.
Now we have XIsprite² , YHsprite² , ZGsprite² , AFsprite² , BGsprite² and CDsprite², along with 6 empty kernels belonging to X , Y , Z , A , B and C
Prototype XIsprite² and YHsprite² into X's empty kernel.
Prototype ZGsprite² and AFsprite² into Y's empty kernel.
Prototype BGsprite² and CDsprite² into Z's empty kernel.
Now we have XIYHsprite³, ZGAFsprite³ and BGCDsprite³, along with 3 empty kernels belonging to A, B and C
Prototype XIYHsprite³ and ZGAFsprite³ into A's Kernel
Now we have XIYHZGAFsprite⁴ and BGCDsprite³, along with 2 empty kernels belonging to B and C.
Prototype XIYHZGAFsprite⁴ and BGCDsprite³ into B's empty kernel
And... CONGRATULATIONS! You have created a sprite with every single player inside of it. A sprite so horrible that it now contains 248832 different Ultimate Selves! Your final sprite is ZIYHGAFBGCDsprite⁵, and you have an empty kernel left over. Do whatever you want with that, it's your choice!
all it takes is one time player really

I think that when sprites are combined, the combination should act like a multiplication. When a sprite becomes one prototyping of another sprite, it is a sprite^2, which fits this idea. So when two sprite^2s are prototypes into the same kernel, it would be sprite^2*sprite^2*sprite (with the last sprite being the kernel), making it a sprite^5. This would make your final sprite ZIYHGAFBGCDsprite^17 if I did my math right.

By power of 17 sprite, the number of total ultimate selves in this one sprite would be 2.2186111e+18.
thanks for the wonderful insight, strider. now, the question is, how many fucking limbs would that sprite have?
They already did this in canwc with aradeadsprite^12