I think it loads them from random.
I think this is an endless loop that cycles through a few different ways of attacking with "splash" at random, using the words said in Pokemon Stadium 2 and a few original stuff.
You have to keep watching to see the more exotic ones, such as "Hyper beam!", the "Phone Call", "Trippin on my grill" and "Go, Ditto!"
AFter awhile however, you'll see the same ones over and over, so it's best to stop watching. However, it is as funny as heck. I'm playing it in the background as I type this, and I still can't stop chuckling.
You'd think they'd run out of PP at some point, and use struggle. Or Hyperbeam. What the f**k do you mean you don't know hyperbeam? Just use SPLAAASH attack!