Get a Goldeen and Seaking (Male) and let it learn Waterfall through leveling up, then breed it with a Female Carvahna. That's the only way you can get that to happen at this point.
Ehhhh, I know enough about my own set up, but If I said that I'm technologically savvy enough to walk you through it, I'd be lying sorry bro. #BlameMe
Ark