First deployed: Colossalcon 2013
Colossalcon is located at the Khalahari resort which features a waterpark, pools, swim-up bar and other watery goodness - so a swimsuit Water-pokemon costume seemed like a good idea XD
I made this in the week between Anime North and Colossal and is probably the simplest costume yet.
A pool noodle carved into the twin tails, stuffed into broadcloth "case" and attached to a pair of hideously bright swim trunks. Blue spandex covered foam attached to wristbands for fins and a wig and I was pretty much done!
(And on a side note I have now made enough pokemon costumes to form my own team XD)