Ah yes, the drain.
Blew that part of the equation since most of the kiddie pools don't come with so I ended up using some HomeDepot plumbing goodies and made my own. Cut a round hole in the side of the tub just above the floor and then cut a short 2" length of 1" PVC and just stuck capped both ends with those round PVC caps. I used some waterproof goop around the hole. It's not pretty but it works.