While I just picked people's names, I never went into detail why I liked them.
Scampali, first of all, sounds very lighthearted and cute, which is what I seem to look for in a name. Not cuteness, but relation to Pokemon's appearance. Next, while the name has nothing to do with shrimp, scamp has a purpose. It means mysterious young person, as SJCrew said, and with further thought, it's true. While CAP10 is small, it will certainly wipe the floor with any one Pokemon it desires. This is the exact opposite of Overkrill, which feels more like the most amazing Pokemon ever, which would mean it would have to counter a lot. The ONLY reason I don't see the name too fit is because it can counter one Pokemon specifically. That's competitive battling. We're making this for competitive battling, but overall it's still just supposed to be a Pokemon. If only it has a moveset to back up the fact it's Scampali, then it would be an amazing name.
Ebion has a distinct feeling to it, and also adds to cuteness, including that little "Ion" that wasn't used often. While "Ebi" is Japanese shrimp, people shouldn't complain that the reference to Shrimp is obvious. A Pokemon to counteract this is easily Pachirisu. Seriously, the Japanese name being the same as English. Why can't Ebion be part Japanese? This also leads back to my claim that the "krill" reference doesn't need priority with that second L.
Prawnto was a close decision for me. Firstly, prawn is shrimp. Those that overly exaggerate that references to shrimp shouldn't be too obvious. This one is obvious, but look closely. The point of the shrimp is to take on one Pokemon and win. Prawnto! Simple concept. BUT, as I have stated earlier, this is relating to competitive battling a little more than I desire, so that's why it's only a fourth pick. Though, like Scampali, if CAP10 can pull off being Prawnto if it were in a real game, it would be amazing as well.
So, this is my order of best to worst:
Ebion > Scampli > Prawnto
I'd put Krilowatt in front but that would be biased. :P My reasons for Krilowatt are already stated.