Fishin, as I understand it, "black comets" are actually a cross between goldfish and koi. They are famous for being somewhat crazy.
I have four fancies in a tank, and the pearlscale is the most people-oriented fish I have seen. She is the poorest swimmer in the tank, but is always the first to the food. She watches me approach, watches my hand, and is in position while the others are dancing around the tank. They are getting smarter and have started following her at feeding time. This is the kind of fish that would be great at learning tricks, but would only flee a predator if the other fish went first. Being the slowest swimmer, that would be goodbye Pearls.
Usually what I called "pond type" goldfish are just called "pond goldfish." There is no other good term for them. Some people say "single tails," but wakin, watonai, and jikin all have double tails. Long bodied or normal bodied has never caught on.