I'm having a hard time understanding the difficulty, here.
You represented that very large number as “G64”. If I want to repeat a loop that gains 1 life each time, my life total can be noted as G64, then G64-2 if I lose 2, etc. So far, no problem.
We aren't going to actually do anything that many times, NAP can still propose a lower number, but even if not, we're just going to have “G64” iterations of something, then an end result.
Pestermite and
Splinter Twin? OK, you now have G64+1 Pestermites. Attack for … well, a LOT.
Also, one billion is 1,000,000,000; one trillion is 1,000,000,000,000. I don't care what the power of 10 is for either, but my calculator makes me think it's 10^9 for billion, 10^12 for trillion … but again, why would it matter?
d:^D